Battery cell and battery pack

Abstract

The application relates to the technical field of batteries and discloses a battery cell and a battery pack, wherein the battery cell mainly comprises a pole group, an insulating film, two first adhesive films and two second adhesive films; the insulating film is wrapped around the outer periphery of the pole group; the two first adhesive films are respectively folded and wrapped around the bottom corners of the insulating film and are located at opposite sides of the insulating film, and the first adhesive film has at least one folded edge after being folded; and the two second adhesive films are respectively wrapped around the outer surfaces of the folded edges of the two first adhesive films and are used for fixing the folded edges. The battery cell of the application wraps the pole group with the insulating film, and then wraps the bottom corners of the insulating film with the two first adhesive films, so that the decline of the insulation performance caused by slight material falling or foreign matter accumulation of pole pieces can be avoided, the use reliability of the insulating film is improved, the use safety and service life of the battery cell are improved, and the folded edges formed after being folded can be prevented from being raised to facilitate the pole group into the shell through the second adhesive film fixing the folded edges of the first adhesive films.

Description

Technical Field

[0001] This invention relates to the field of battery technology, specifically to battery cells and battery packs. Background Technology

[0002] With the widespread application of new energy batteries in electric vehicles and energy storage systems, higher requirements are being placed on their energy density, cycle life, and safety and reliability. In the manufacturing process of new energy batteries, an insulating film, such as a Mylar film, is usually wrapped around the outer periphery of the electrode assembly of the cell to isolate the electrode assembly from the casing, prevent short circuits between the two, and provide withstand voltage protection. The electrode assembly covered with the insulating film is then assembled into the casing, and finally the casing and cover are sealed to form a sealed space to protect the electrode assembly.

[0003] like Figure 1 As shown, after the existing insulating film 2' covers the outer periphery of the electrode assembly, the top of the insulating film 2' extends to the side of the lower plastic 501' on the cover plate 5' and is fixed by heat fusion, as shown in the figure. Figure 1 As shown at point A in the diagram.

[0004] like Figure 2 and Figure 3 As shown, for ease of installation, the existing insulating film 2' in its unfolded state typically has multiple notches, such as... Figure 3 As shown in C, the four corner areas at the bottom of the electrode assembly form gaps that are not completely covered after the insulating film 2' is wrapped around them. These gaps are as follows: Figure 2 As shown in B in the diagram. During subsequent use of the battery cell, this gap area is prone to a decrease in insulation performance due to slight material loss from the electrode or accumulation of foreign objects, causing local short circuits and seriously affecting the safety and service life of the battery cell. Summary of the Invention

[0005] This invention provides a battery cell and battery pack to solve the problem that after the existing insulating film is wrapped around the outer periphery of the electrode assembly, there is a gap area at the bottom corner of the electrode assembly, which is prone to a decrease in insulation performance due to slight material loss of the electrode sheet or accumulation of foreign matter.

[0006] In a first aspect, the present invention provides a battery cell, comprising:

[0007] pole group;

[0008] An insulating film is formed and covers the outer periphery of the electrode assembly;

[0009] Two first adhesive films are folded and wrapped around the bottom corner of the insulating film along the Z direction, and are located on opposite sides of the insulating film along the X direction. The first adhesive film has at least one folded edge after being folded.

[0010] Two second adhesive films are respectively wrapped around the outer surface of the flanges of the two first adhesive films to fix the flanges.

[0011] Beneficial effects: The battery cell of this invention utilizes an insulating film to cover the electrode assembly, providing insulation and withstand voltage protection. Furthermore, two first adhesive films cover the bottom corners of the insulating film, protecting these corners and preventing a decrease in insulation performance due to minor electrode material loss or foreign object accumulation. This improves the reliability of the insulating film and enhances the safety and lifespan of the battery cell. Moreover, the second adhesive film secures the folded edges formed by the first adhesive film, preventing the edges from lifting and facilitating the insertion of the electrode assembly into the casing.

[0012] In one optional embodiment, the first adhesive film includes: a base film, two large face films, a first flanged film, and two second flanged films, wherein the first adhesive film is in an unfolded state;

[0013] In the unfolded state, the two large face films are respectively disposed on opposite sides of the base film in the Y direction, the first folded edge film is disposed on one side of the base film in the X direction, and the two second folded edge films are respectively disposed on one side of the two large face films in the X direction and connected to the adjacent first folded edge film. Each second folded edge film is provided with a diagonal crease line, which extends from the corner where the base film and the large face film intersect to the end face of the second folded edge film away from the large face film in the X direction, and the two diagonal crease lines are far apart from each other in the extension direction.

[0014] Beneficial effects: After the first film is folded, the bottom film, the two large films, the first folded edge film, and the second folded edge film work together to completely wrap the bottom corner of the insulating film, thereby preventing insulation failure due to slight material loss from the electrode sheet or accumulation of foreign objects at the corner.

[0015] In one optional embodiment, the first adhesive film has a folded state, wherein in the folded state, the two large films are respectively attached to the two large surfaces of the insulating film along the Y direction;

[0016] The length of the large mask along the X direction is L1, which satisfies 3 mm ≤ L1 ≤ 50 mm;

[0017] And / or, the length of the large mask along the Z direction is L2, satisfying 5 mm ≤ L2 ≤ 50 mm.

[0018] Beneficial effects: By attaching two large films to the two large surfaces of the insulating film, the bonding area between the first adhesive film and the insulating film can be increased, improving the bonding strength between the two. By controlling L1 within a suitable range, sufficient bonding area of ​​the first adhesive film in the X direction can be ensured, preventing edge lifting due to insufficient bonding area and avoiding material waste. By controlling L2 within a suitable range, sufficient bonding area of ​​the first adhesive film in the Z direction can be ensured, making the first and second edge films firmly bonded, preventing lifting and rebound of the first and second edge films, facilitating smooth insertion of the electrode assembly into the housing, preventing scratches on the electrode assembly, and avoiding material waste.

[0019] In one optional embodiment, in the folded state, the bottom film is attached to the bottom surface of the insulating film along the Z direction, the two second folded films are attached to the narrow side of the insulating film in the X direction, and the first folded film is attached to the outer surface of the two second folded films.

[0020] The second adhesive film includes a first sub-film and a second sub-film connected to each other. The first sub-film is attached to the outer surface of the first flanged film and extends out of the first flanged film along the Z direction and is attached to the narrow side of the insulating film. The second sub-film is attached to the outer surface of the bottom film.

[0021] Beneficial effects: The first sub-film can cover and fix the first and second flanged films. Simultaneously, the first sub-film extends along the Z-direction beyond the first flanged film and is attached to the narrow side of the insulating film, further enhancing the firmness of the first sub-film to the first and second flanged films. By setting the second sub-film, the base film can be reinforced, further reducing the risk of the first and second flanged films lifting or springing back.

[0022] In one alternative embodiment, along the Z direction, the first sub-film extends beyond the first flange film by a length L3, satisfying 3 mm ≤ L3 ≤ 50 mm.

[0023] Beneficial effects: By controlling L3 within a suitable range, the first sub-film has sufficient additional bonding length, effectively preventing the first and second flange films from detaching, and also avoiding material waste and increased costs caused by the first sub-film being too long.

[0024] In one alternative embodiment, the length of the second sub-membrane along the X direction is L4, satisfying 3 mm ≤ L4 ≤ 50 mm.

[0025] Beneficial effects: By controlling L4 within a suitable range, sufficient bonding area of ​​the second sub-film at the bottom film is ensured, guaranteeing the reliability between the second adhesive film and the bottom film, preventing the second adhesive film from lifting and failing under stress, and avoiding material waste and increased costs caused by an excessively long second sub-film.

[0026] In one optional embodiment, in the folded state, the bottom film is attached to the narrow side of the insulating film in the X direction, the two second folded films are attached to the bottom surface of the insulating film in the Z direction, and the first folded film is attached to the outer surface of the two second folded films.

[0027] Beneficial effects: By attaching the bottom film to the narrow side and the second flange film to the bottom, effective coverage and protection of the bottom corner can also be achieved, increasing process flexibility.

[0028] In one optional embodiment, the thickness of the first adhesive film is T1, which satisfies 0.03 mm ≤ T1 ≤ 0.5 mm;

[0029] The thickness of the second adhesive film is T2, which satisfies 0.01 mm ≤ T2 ≤ 0.3 mm.

[0030] Beneficial effects: By controlling T1 within a suitable range, the first adhesive film possesses both good insulation properties and flexibility, ensuring sufficient dielectric strength to prevent voltage breakdown, while avoiding excessive thickness that could lead to stiffness and warping at corner folds. By controlling T2 within a suitable range, the second adhesive film possesses the necessary mechanical strength to secure the flange, preventing deformation or breakage of the second adhesive film in subsequent processes that could lead to fixing failure, while also avoiding material waste and increased costs.

[0031] In one optional embodiment, the width of the second adhesive film along the Y direction is W1, and the width of the insulating film along the Y direction is W2, satisfying 0.5≤W1 / W2<1, 5 mm≤W1≤80 mm, and 10 mm≤W2≤100 mm.

[0032] Beneficial effects: By controlling W1, W2, and W1 / W2 within a suitable range, the second adhesive film has sufficient constraint width on the flange of the first adhesive film, so that the second adhesive film fully covers and constrains both sides of the flange, preventing the flange from lifting due to insufficient coverage width, thereby ensuring that the electrode assembly can be smoothly installed into the housing, and also avoiding the electrode assembly being scratched.

[0033] Secondly, the present invention also provides a battery pack comprising: at least one of the above-described battery cells.

[0034] Beneficial effects: Since the battery pack includes battery cells, it has the same effects as the battery cells, which will not be repeated here. Attached Figure Description

[0035] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0036] Figure 1 A schematic diagram of existing battery cells;

[0037] Figure 2 A side view of an existing battery cell;

[0038] Figure 3 This is a schematic diagram of the existing insulating film in its unfolded state.

[0039] Figure 4 This is a schematic diagram of the battery cell structure according to an embodiment of the present invention;

[0040] Figure 5 This is a side view of the battery cell according to an embodiment of the present invention;

[0041] Figure 6 This is a front view of the battery cell according to an embodiment of the present invention;

[0042] Figure 7 This is a schematic diagram of the first adhesive film of the battery cell in the unfolded state according to an embodiment of the present invention;

[0043] Figure 8 This is a schematic diagram of the first adhesive film covering the insulating film of the battery cell according to an embodiment of the present invention;

[0044] Figure 9 This is another schematic diagram of the first adhesive film covering the insulating film of the battery cell according to an embodiment of the present invention;

[0045] Figure 10 This is a schematic diagram of the structure of a battery cell according to another embodiment of the present invention.

[0046] Explanation of reference numerals in the attached figures:

[0047] Existing technology: 2', insulating film; 5', cover plate; 501', lower plastic;

[0048] This application includes: 1. Electrode assembly; 2. Insulating film; 201. Large surface; 202. Bottom surface; 203. Narrow side surface; 3. First adhesive film; 301. Flanged edge; 302. Bottom film; 303. Large surface film; 304. First flanged edge film; 305. Second flanged edge film; 3051. Diagonal crease line; 306. First crease line; 307. Second crease line; 4. Second adhesive film; 401. First sub-film; 402. Second sub-film. Detailed Implementation

[0049] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0050] In the description of the embodiments of the present invention, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present invention, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces), unless otherwise explicitly specified.

[0051] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0052] In the description of the embodiments of this invention, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0053] The battery cell mentioned in this embodiment of the invention is the smallest unit that makes up a battery, and it can independently perform the functions of charging and discharging. This embodiment of the invention does not impose any particular limitations on the type or shape of the battery cell; it can be a blade cell, a prismatic cell, or other types of battery cells. The battery cell in this embodiment of the invention can be a lithium-ion cell, a potassium-ion cell, a sodium-ion cell, a lithium-sulfur cell, etc., with lithium-ion cells being particularly preferred.

[0054] A battery cell typically includes an electrode assembly, also known as an electrode group. The electrode group consists of a positive electrode, a negative electrode, and a separator. During the charging and discharging process, active ions (such as lithium ions) repeatedly insert and extract between the positive and negative electrode plates. The separator, positioned between the positive and negative electrode plates, prevents short circuits while allowing active ions to pass through.

[0055] The battery cell also includes a casing and a cover plate. The casing and cover plate, when connected, form a sealed space encapsulating the electrode assembly and electrolyte. The casing is generally made of metal materials, such as steel, aluminum, or composite metals (e.g., copper-aluminum composite). The cover plate can also integrate components such as terminals, explosion-proof valves, and electrolyte filling holes. The ends of the electrode assembly taper to form tabs, which are electrically connected to the terminals to enable charging and discharging of the electrode assembly.

[0056] To prevent short circuits between the electrode assembly and the casing, and for withstand voltage protection, existing electrode assemblies are typically covered with an insulating film. For ease of installation, the existing insulating film usually has multiple notches when unfolded. Due to these notches, gaps easily form at the four corners of the electrode assembly's bottom after the insulating film is applied. During subsequent use of the battery cell, these gaps are prone to insulation degradation due to minor electrode chipping or foreign object accumulation, leading to localized short circuits and severely impacting the cell's safety and lifespan.

[0057] The following is combined Figures 4 to 10 The following describes embodiments of the present invention.

[0058] According to an embodiment of the present invention, in one aspect, a battery cell is provided, mainly comprising: an electrode assembly 1, an insulating film 2, two first adhesive films 3, and two second adhesive films 4. The insulating film 2 covers the outer periphery of the electrode assembly 1. The two first adhesive films 3 are respectively folded and covered at the bottom corner of the insulating film 2 along the Z direction, and located on opposite sides of the insulating film 2 along the X direction. The first adhesive film 3 has at least one flange 301 after folding. The two second adhesive films 4 are respectively covered on the outer surface of the flange 301 of the two first adhesive films 3 for fixing the flange 301.

[0059] Therefore, the battery cell provided in this embodiment of the invention utilizes an insulating film 2 to cover the electrode assembly 1, providing insulation and withstand voltage protection. Furthermore, two first adhesive films 3 cover the bottom corners of the insulating film 2, protecting these corners and preventing a decrease in insulation performance due to slight material loss from the electrode sheets or accumulation of foreign matter. This improves the reliability of the insulating film 2 and enhances the safety and lifespan of the battery cell. Moreover, the second adhesive film 4 secures the folded edge 301 formed by the first adhesive film 3, preventing the edge 301 from lifting and facilitating the insertion of the electrode assembly 1 into the casing.

[0060] Specifically, the X direction is also the length direction of pole group 1, such as... Figure 4 As shown by arrow X in the diagram, the Y direction is also the width direction of pole group 1, as shown in the diagram. Figure 4 As shown by the arrow Y in the diagram, the Z direction is also the height direction of pole group 1, as shown in the diagram. Figure 4 As indicated by arrow Z in the diagram.

[0061] The battery cell also includes components such as a casing and a cover plate (not shown in the figure). The top surface of the electrode assembly 1 is provided with a tab, which is electrically connected to the electrode post on the cover plate. After the electrode assembly 1 is covered with an insulating film 2, it is assembled in the casing. The casing is generally a square shell, and the electrode assembly 1 is correspondingly rectangular. After the insulating film 2 is covered with the electrode assembly 1, it forms four corners at the bottom.

[0062] The first adhesive film 3 has an unfolded state and a folded state. The unfolded state refers to the first adhesive film 3 being laid out as a sheet, and the folded state refers to the first adhesive film 3 being folded along the fold line and wrapped around the insulating film 2. The first adhesive film 3 is usually supplied in rolls. In this embodiment of the invention, the first adhesive film 3 can be directly cut from the roll into rectangular sheets without the need for additional cuts or notches. The first adhesive film 3 is directly folded along the fold line and wrapped around the bottom corner of the insulating film 2, simplifying manufacturing, significantly reducing usage costs, and improving production efficiency. Figure 4 As shown, since the first adhesive film 3 is a rectangular sheet, it will form a flange 301 after being wrapped around the bottom corner of the insulating film 2.

[0063] It should be noted that the embodiments of the present invention do not limit the materials of the first adhesive film 3 and the second adhesive film 4, and any existing material can be selected as needed. Since the electrolyte needs to flow inside the electrode assembly 1, the first adhesive film 3 and the second adhesive film 4 need to be resistant to the electrolyte. For example, the first adhesive film 3 and the second adhesive film 4 can be made of polypropylene (PP), polyethylene terephthalate (PET), polyimide (PI), etc.

[0064] Furthermore, the embodiments of the present invention do not limit the material of the insulating film 2. Any existing material can be selected as needed. The insulating film 2 also needs to be resistant to electrolyte. For example, the insulating film 2 can be made of polypropylene film (PP film), polyethylene terephthalate film (PET film), polyimide film (PI film), etc.

[0065] In one embodiment, such as Figure 5 , Figure 6 and Figure 7 As shown, the first adhesive film 3 includes: a base film 302, two large face films 303, a first edge-turning film 304, and two second edge-turning films 305.

[0066] In the unfolded state, two large face films 303 are respectively located on opposite sides of the base film 302 in the Y direction. A first folded edge film 304 is located on one side of the base film 302 in the X direction. Two second folded edge films 305 are respectively located on one side of the two large face films 303 in the X direction and connected to the adjacent first folded edge film 304. Each second folded edge film 305 has a diagonal crease line 3051, which extends from the corner where the base film 302 intersects with the large face film 303 towards the end face of the second folded edge film 305 in the X direction away from the large face film 303, and the two diagonal crease lines 3051 are far apart from each other in the direction of extension.

[0067] Furthermore, the first adhesive film 3 has two first crease lines 306 extending along the X direction and one second crease line 307 extending along the Y direction. The two first crease lines 306 and one second crease line 307 intersect each other to divide the first adhesive film 3 into a base film 302, two large surface films 303, a first edge-folding film 304, and two second edge-folding films 305. The first adhesive film 3 is folded along the first crease line 306, the second crease line 307, and the diagonal crease line 3051 to cover the corners of the insulating film 2.

[0068] After the first adhesive film 3 is folded, the bottom film 302, the two large face films 303, the first folded edge film 304, and the second folded edge film 305 work together to completely wrap the bottom corner of the insulating film 2, thereby preventing insulation failure due to slight material loss from the electrode sheet or accumulation of foreign objects at the corner.

[0069] In one embodiment, such as Figure 6 As shown, in the folded state, the two large films 303 are respectively attached to the two large surfaces 201 of the insulating film 2 along the Y direction.

[0070] Furthermore, the length of the large mask 303 along the X direction is L1, which satisfies 3 mm ≤ L1 ≤ 50 mm.

[0071] And / or, the length of the large mask 303 along the Z direction is L2, which satisfies 5 mm ≤ L2 ≤ 50 mm.

[0072] By attaching two large adhesive films 303 to the two large surfaces 201 of the insulating film 2, the bonding area between the first adhesive film 3 and the insulating film 2 can be increased, thus improving the bonding strength between the two. By controlling L1 within a suitable range, it can be ensured that the first adhesive film 3 has sufficient bonding area in the X direction, preventing edge lifting due to insufficient bonding area and avoiding material waste. By controlling L2 within a suitable range, it can be ensured that the first adhesive film 3 has sufficient bonding area in the Z direction, making the first flange film 304 and the second flange film 305 firmly bonded, preventing the first flange film 304 and the second flange film 305 from lifting and rebounding, facilitating the smooth insertion of the electrode assembly 1 into the shell, preventing scratches on the electrode assembly 1, and avoiding material waste.

[0073] For example, in an embodiment of the present invention, L1 can be any value of 3 mm, 10 mm, 15 mm, 20 mm, 30 mm, 40 mm, 50 mm or a value between any two values, and L2 can be any value of 5 mm, 10 mm, 15 mm, 20 mm, 30 mm, 40 mm, 50 mm or a value between any two values.

[0074] In one embodiment, such as Figure 4 As shown, in the folded state, the bottom film 302 is attached to the bottom surface 202 of the insulating film 2 along the Z direction, and the two second flange films 305 are attached to the narrow side surface 203 of the insulating film 2 along the X direction. The first flange film 304 is attached to the outer surface of the two second flange films 305. The first flange film 304 is folded to form a flange 301.

[0075] like Figure 5 and Figure 6 As shown, the second adhesive film 4 includes a first sub-film 401 and a second sub-film 402 connected to each other. The first sub-film 401 is attached to the outer surface of the first flange film 304 and extends out of the first flange film 304 along the Z direction and is attached to the narrow side surface 203 of the insulating film 2. The second sub-film 402 is attached to the outer surface of the bottom film 302.

[0076] The first sub-film 401 covers and secures the first flanged film 304 and the second flanged film 305. Simultaneously, the first sub-film 401 extends along the Z-direction beyond the first flanged film 304 and is attached to the narrow side 203 of the insulating film 2, further enhancing the firmness of the first sub-film 401 over the first flanged film 304 and the second flanged film 305. By providing the second sub-film 402, the base film 302 can be reinforced, further reducing the risk of the first flanged film 304 and the second flanged film 305 lifting or springing back.

[0077] Furthermore, in one embodiment, such as Figure 5 As shown, along the Z direction, the first sub-film 401 extends out of the first flange film 304 by a length L3, satisfying 3 mm ≤ L3 ≤ 50 mm. By controlling L3 within a suitable range, it is ensured that the first sub-film 401 has sufficient additional bonding length, effectively preventing the first flange film 304 and the second flange film 305 from detaching, and also avoiding material waste and cost increase caused by the first sub-film 401 being too long.

[0078] For example, in an embodiment of the present invention, L3 can be any value among 3 mm, 10 mm, 15 mm, 20 mm, 30 mm, 40 mm, and 50 mm, or a value between any two values.

[0079] Furthermore, in one embodiment, such as Figure 6As shown, along the X direction, the length of the second sub-film 402 is L4, satisfying 3mm≤L4≤50 mm. By controlling L4 within a suitable range, sufficient bonding area is ensured for the second sub-film 402 at the base film 302, guaranteeing the reliability between the second adhesive film 4 and the base film 302, preventing the second adhesive film 4 from warping and failing under stress, and also avoiding material waste and increased costs caused by an excessively long second sub-film 402.

[0080] For example, in an embodiment of the present invention, L4 can be any value among 3 mm, 10 mm, 15 mm, 20 mm, 30 mm, 40 mm, and 50 mm, or a value between any two values.

[0081] The assembly process of the first adhesive film 3 in this embodiment of the invention is as follows:

[0082] like Figure 7 and Figure 8 As shown, first, the bottom film 302 is attached to the bottom surface 202 of the insulating film 2. Then, the two large films 303 are folded along the first fold line 306 and attached to the two large surfaces 201 of the insulating film 2. Finally, they are folded along the second fold line 307 and the diagonal fold line 3051 respectively, so that the two second folded films 305 partially overlap and are attached to the narrow side surface 203 of the insulating film 2. The first folded film 304 is attached to the outer side surface of the two second folded films 305. Figure 9 As shown.

[0083] In another embodiment, such as Figure 10 As shown, in the folded state, the bottom film 302 is attached to the narrow side 203 of the insulating film 2 in the X direction, and two second folded edge films 305 are attached to the bottom surface 202 of the insulating film 2 along the Z direction. The first folded edge film 304 is attached to the outer surface of the two second folded edge films 305. By attaching the bottom film 302 to the narrow side 203 and the second folded edge films 305 to the bottom surface 202, effective coverage and protection of the bottom corner can also be achieved, increasing process flexibility.

[0084] In addition, in this embodiment, the various dimensional parameters of the first sub-membrane 401 and the second sub-membrane 402 described above are also applicable and will not be repeated here.

[0085] In one embodiment, the thickness of the first adhesive film 3 is T1, satisfying 0.03 mm ≤ T1 ≤ 0.5 mm. By controlling T1 within a suitable range, the first adhesive film 3 possesses both good insulation properties and flexibility, ensuring sufficient dielectric strength to prevent voltage breakdown, while avoiding the risk of warping due to excessive thickness causing the material to become too stiff at corners and folds.

[0086] For example, in an embodiment of the present invention, T1 can be any value among 0.03 mm, 0.05 mm, 0.1 mm, 0.15 mm, 0.2 mm, 0.3 mm, 0.4 mm, and 0.5 mm, or a value between any two values.

[0087] In one embodiment, the thickness of the second adhesive film 4 is T2, satisfying 0.01 mm ≤ T2 ≤ 0.3 mm. By controlling T2 within a suitable range, the second adhesive film 4 has the necessary mechanical strength to fix the flange 301, that is, to fix the first flange film 304 and the second flange film 305, preventing the second adhesive film 4 from deforming or breaking in subsequent processes, thus causing fixing failure, while avoiding material waste and increased costs.

[0088] For example, in an embodiment of the present invention, T2 can be any value among 0.01 mm, 0.03 mm, 0.06 mm, 0.09 mm, 0.12 mm, 0.2 mm, 0.25 mm, and 0.3 mm, or a value between any two values.

[0089] In one embodiment, such as Figure 5 As shown, the width of the second adhesive film 4 along the Y direction is W1, and the width of the insulating film 2 along the Y direction is W2, satisfying 0.5≤W1 / W2<1, 5 mm≤W1≤80 mm, and 10 mm≤W2≤100 mm.

[0090] By controlling W1, W2, and W1 / W2 within a suitable range, the second adhesive film 4 is ensured to have sufficient constraint width on the flange 301 of the first adhesive film 3, so that the second adhesive film 4 fully covers and constrains both sides of the flange 301, preventing the flange 301 from lifting due to insufficient coverage width, thereby ensuring that the electrode assembly 1 can be smoothly installed into the housing, and also avoiding the electrode assembly 1 from being scratched.

[0091] For example, in an embodiment of the present invention, W1 can be 5 mm and W2 can be 10 mm, then W1 / W2 is 0.5; or W1 can be 40 mm and W2 can be 60 mm, then W1 / W2 is 0.67; or W1 can be 80 mm and W2 can be 100 mm, then W1 / W2 is 0.8, etc.

[0092] In one embodiment, the insulating film 2 can be in the form of a rectangular sheet and folded over to cover the outer periphery of the electrode assembly 1 without the need for a notch, thus further improving insulation reliability. Moreover, after the insulating film 2 is folded, it forms a partially overlapping folded edge, which is located on the side of the electrode assembly 1 along the X direction. At this time, the second adhesive film 4 extends to the folded edge and can also help fix the folded edge of the insulating film 2.

[0093] The following detailed description of the battery cell of the present invention, in conjunction with specific embodiments, is intended to limit the scope of protection claimed by the present invention.

[0094] The battery cell includes: electrode group 1, insulating film 2, two first adhesive films 3, two second adhesive films 4, housing and cover plate.

[0095] The top surface of electrode assembly 1 is provided with a tab, which is electrically connected to the electrode post on the cover plate. After being covered with insulating film 2, electrode assembly 1 is assembled inside the housing. The housing is a square shell, and electrode assembly 1 is correspondingly rectangular. Insulating film 2 covers the outer periphery of electrode assembly 1. After covering electrode assembly 1, insulating film 2 forms four corners at the bottom.

[0096] Two first adhesive films 3 are folded over and wrapped around the bottom corner of the insulating film 2 along the Z direction, and located on opposite sides of the insulating film 2 along the X direction. Each first adhesive film 3 has at least one flange 301 after folding. Two second adhesive films 4 are wrapped around the outer surface of the flanges 301 of the two first adhesive films 3 to fix the flanges 301. The first adhesive films 3 and second adhesive films 4 are made of PP film, and the insulating film 2 is made of PET film.

[0097] The first adhesive film 3 has two first crease lines 306 extending along the X direction and a second crease line 307 extending along the Y direction. The two first crease lines 306 and the second crease line 307 intersect each other to divide the first adhesive film 3 into a base film 302, two large face films 303, a first edge-turning film 304, and two second edge-turning films 305.

[0098] In the unfolded state, two large face films 303 are respectively located on opposite sides of the base film 302 in the Y direction. A first folded edge film 304 is located on one side of the base film 302 in the X direction. Two second folded edge films 305 are respectively located on one side of the two large face films 303 in the X direction and connected to the adjacent first folded edge film 304. Each second folded edge film 305 has a diagonal crease line 3051, which extends from the corner where the base film 302 intersects with the large face film 303 towards the end face of the second folded edge film 305 in the X direction away from the large face film 303, and the two diagonal crease lines 3051 are far apart from each other in the direction of extension.

[0099] The second adhesive film 4 includes a first sub-film 401 and a second sub-film 402 connected to each other.

[0100] The assembly process of the first adhesive film 3 and the second adhesive film 4 is as follows:

[0101] First, the bottom film 302 is attached to the bottom surface 202 of the insulating film 2. Then, the two large surface films 303 are folded along the first fold line 306 and attached to the two large surfaces 201 of the insulating film 2. Finally, they are folded along the second fold line 307 and the diagonal fold line 3051 respectively, so that the two second folded edge films 305 partially overlap and are attached to the narrow side surface 203 of the insulating film 2. The first folded edge film 304 is attached to the outer surface of the two second folded edge films 305. Finally, the first sub-film 401 is attached to the outer surface of the first folded edge film 304, and extends the first folded edge film 304 along the Z direction and is attached to the narrow side surface 203 of the insulating film 2. The second sub-film 402 is attached to the outer surface of the bottom film 302.

[0102] After the first adhesive film 3 is folded, the bottom film 302, the two large outer films 303, the first folded edge film 304, and the second folded edge film 305 work together to completely cover the bottom corner of the insulating film 2, thereby preventing insulation failure due to slight material loss from the electrode sheet or accumulation of foreign objects at the corner. The second adhesive film 4 can effectively fix the first adhesive film 3, preventing the first folded edge film 304 and the second folded edge film 305 on the outer side from lifting after the first adhesive film 3 is folded.

[0103] The length L1 of the large film 303 along the X direction is 20 mm. The length L2 of the large film 303 along the Z direction is 25 mm, ensuring that the large film 303 and the two large surfaces 201 of the insulating film 2 have sufficient bonding area, avoiding the edge of the first adhesive film 3 from lifting, and facilitating the smooth insertion of the electrode assembly 1 into the shell.

[0104] Along the Z direction, the first sub-film 401 extends out of the first flange film 304 by a length L3 of 20 mm, ensuring that the first sub-film 401 has sufficient adhesive length to effectively prevent the first flange film 304 and the second flange film 305 from separating.

[0105] Along the X direction, the length L4 of the second sub-film 402 is 20 mm, ensuring that the second sub-film 402 has sufficient bonding area at the bottom film 302, guaranteeing the reliability between the second adhesive film 4 and the bottom film 302, and preventing the second adhesive film 4 from lifting and failing under force.

[0106] The first sub-film 401 and the second sub-film 402 are of equal width. The width W1 of the second adhesive film 4 along the Y direction is 40 mm. The width W2 of the insulating film 2 along the Y direction is 50 mm, so W1 / W2 is 0.8, which ensures that the second adhesive film 4 has sufficient constraint width on the flange 301 of the first adhesive film 3, so that the second adhesive film 4 fully covers and constrains both sides of the flange 301, preventing the flange 301 from lifting due to insufficient coverage width, thereby ensuring that the electrode assembly 1 can be stably installed into the housing, and also avoiding scratches on the electrode assembly 1.

[0107] The thickness T1 of the first adhesive film 3 is 0.3 mm, which gives the first adhesive film 3 both good insulation performance and flexibility, ensures sufficient dielectric strength to prevent voltage breakdown, and avoids the risk of the material becoming too hard at the corners and folds due to excessive thickness, which may cause it to warp.

[0108] The thickness T2 of the second adhesive film 4 is 0.2 mm, which gives the second adhesive film 4 the necessary mechanical strength to fix the flange 301, that is, to fix the first flange film 304 and the second flange film 305, and to prevent the second adhesive film 4 from deforming or breaking in subsequent processes, which would lead to fixing failure.

[0109] According to an embodiment of the present invention, in another aspect, a battery pack is also provided, comprising: at least one of the above-described battery cells.

[0110] Since the battery pack includes battery cells and has the same effect as the battery cells, it will not be elaborated on here.

[0111] In embodiments of the present invention, a "battery pack" is formed by combining a certain number of battery cells into a battery module and placing it in a housing in order to protect the battery cells from external impacts, heat, vibration, etc. The battery pack also includes a battery management system (BMS), an electrical connection system (high-voltage / low-voltage connectors, wiring harnesses, etc.), structural components (casing, brackets, etc.), and protective components, forming a complete functional unit that can directly output electrical energy.

[0112] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A battery cell, characterized in that, include: pole group; An insulating film is formed and covers the outer periphery of the electrode assembly; Two first adhesive films are folded and wrapped around the bottom corner of the insulating film along the Z direction, and are located on opposite sides of the insulating film along the X direction. The first adhesive film has at least one folded edge after being folded. Two second adhesive films are respectively wrapped around the outer surface of the flange of the two first adhesive films to fix the flange; The first adhesive film includes: a base film, two large face films, a first edge-folding film, and two second edge-folding films, and the first adhesive film is in an unfolded state; In the unfolded state, the two large face films are respectively disposed on opposite sides of the base film in the Y direction, the first flange film is disposed on one side of the base film in the X direction, and the two second flange films are respectively disposed on one side of the two large face films in the X direction and connected to the adjacent first flange film. Each second flange film is provided with a diagonal crease line. The diagonal crease line extends from the corner where the base film and the large face film intersect to the end face of the second flange film in the X direction away from the large face film, and the two diagonal crease lines are far apart from each other in the extension direction. The first adhesive film has a folded state, in which the two large films are respectively attached to the two large surfaces of the insulating film along the Y direction; The length of the large mask along the X direction is L1, which satisfies 3 mm ≤ L1 ≤ 50 mm; And / or, the length of the large mask along the Z direction is L2, satisfying 5 mm ≤ L2 ≤ 50 mm.

2. The battery cell according to claim 1, characterized in that, In the folded state, the bottom film is attached to the bottom surface of the insulating film along the Z direction, the two second folded films are attached to the narrow side of the insulating film in the X direction, and the first folded film is attached to the outer surface of the two second folded films. The second adhesive film includes a first sub-film and a second sub-film connected to each other. The first sub-film is attached to the outer surface of the first flanged film and extends out of the first flanged film along the Z direction and is attached to the narrow side of the insulating film. The second sub-film is attached to the outer surface of the bottom film.

3. The battery cell according to claim 2, characterized in that, Along the Z direction, the first sub-membrane extends beyond the first flanged membrane by a length of L3, satisfying 3 mm ≤ L3 ≤ 50 mm.

4. The battery cell according to claim 2, characterized in that, Along the X direction, the length of the second submembrane is L4, which satisfies 3 mm ≤ L4 ≤ 50 mm.

5. The battery cell according to claim 1, characterized in that, In the folded state, the bottom film is attached to the narrow side of the insulating film in the X direction, the two second folded films are attached to the bottom surface of the insulating film in the Z direction, and the first folded film is attached to the outer surface of the two second folded films.

6. The battery cell according to any one of claims 1 to 5, characterized in that, The thickness of the first adhesive film is T1, which satisfies 0.03 mm ≤ T1 ≤ 0.5 mm; The thickness of the second adhesive film is T2, which satisfies 0.01 mm ≤ T2 ≤ 0.3 mm.

7. The battery cell according to any one of claims 1 to 5, characterized in that, The width of the second adhesive film along the Y direction is W1, and the width of the insulating film along the Y direction is W2, satisfying 0.5≤W1 / W2<1, 5 mm≤W1≤80 mm, and 10 mm≤W2≤100 mm.

8. A battery pack, characterized in that, include: At least one battery cell according to any one of claims 1 to 7.

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