Battery cell and battery pack
By designing the optimized first folding structure in the edge sealing area of the battery cell, the problems of lifting and poor sealing of the battery cell folding structure are solved, more stable folding and higher sealing are achieved, and the safety and compactness of the battery cell are improved.
Patent Information
- Application Number
- CN202411807327.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-10
- Publication Date
- 2025-03-14
AI Technical Summary
The folded edge structure of the existing battery cell is prone to curling and deforming after folding, resulting in poor folding edges. The raised folded edge section is prone to damage the adjacent folded edge section or the side of the packaging body, affecting the sealing effect of the packaging film.
A battery cell is designed, and its edge sealing area includes an extension and a first folding structure. The first folding structure consists of a first folding section, a second folding section and a third folding section sequentially connected. By optimizing the length and connection method of these folding sections, it is ensured that the folding section can be fit stably and prevented from being raised.
It effectively prevents the lifting and damage of the folded edge section, improves the sealing property of the packaging film and the safety performance of the battery cell, and improves the compactness and volume energy density of the battery cell.
Smart Images
Figure CN119627318A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of battery cells, and in particular to a battery cell and a battery pack. Background Art
[0002] The soft-pack battery mainly includes a pole group and a packaging film. The packaging film includes a packaging body and a sealing edge area. The packaging body wraps the pole group, and then the packaging film outside the pole group is hot-pressed to seal the pole group in the packaging film. The packaging film after hot pressing forms a sealing edge area, and the sealing edge area extends outward roughly parallel to the large surface of the battery cell. In order to reduce the space occupied by the sealing edge area in the width direction of the battery cell, the sealing edge area is bent toward the side of the battery cell to form a folding structure. After folding, the existing folding structure is prone to warping and deformation between the sections of the folding structure, resulting in the inability to effectively fit the bent sections, resulting in poor folding. The warped folding section is prone to damage the adjacent folding section or the side of the packaging body, thereby causing damage to the packaging film and affecting the sealing effect of the packaging film. Summary of the invention
[0003] In view of this, the present invention provides a battery cell and a battery pack to solve the problem in the prior art that the folded edge sections of the folded edge structure of the battery cell cannot be effectively fitted together, resulting in the folded edge sections being easily warped and damaging the folded edge sections adjacent to the warped folded edge sections or the side of the packaging body.
[0004] In a first aspect, the present invention provides a battery cell, comprising:
[0005] Pole group;
[0006] A packaging film comprises a packaging body and an edge sealing area, wherein the packaging body is coated on the outside of the electrode group, the edge sealing area is located outside the electrode group, the edge sealing area comprises an extension portion and a first folding structure, the extension portion extends toward the outside of the electrode group, the first folding structure comprises a first folding section, a second folding section and a third folding section connected in sequence; one end of the third folding section is connected to the extension portion, and the other end is bent relative to the extension portion, the second folding section is bent inwardly and toward the extension portion, the first folding section is bent away from the extension portion, and the two sides of the first folding section are attached to the inner wall surface of the third folding section and the outer wall surface of the second folding section; the length of the first folding section is L1, the length of the second folding section is L2, and the length of the third folding section is L3, A distance D1 is provided between one end of the first folding section away from the extending portion and a connection area between the second folding section and the third folding section, and D1 is ≥ 1 mm.
[0007] Beneficial effect: The first folding structure of the battery cell of this structure includes a first folding section, a second folding section and a third folding section, and the length of the first folding section and the second folding section meets This arrangement can ensure that the first folding section has sufficient length, ensure the extension length of the first folding section on the second folding section, avoid the first folding section being too short and curling up after folding, and ensure that the first folding section is stably and effectively attached to the second folding section. The end of the first folding section is a cutting edge, which can prevent the cutting edge from damaging the third folding section; at the same time, the first folding section is located between the second folding section and the third folding section, so that the cutting edge is away from the side of the packaging body, which can effectively prevent the first folding section from damaging the side of the packaging body. At the same time, the lengths of the first folding section and the second folding section meet D1≥1mm, such a setting can prevent the length of the first folding edge section from being too long, prevent the end of the first folding edge section away from the extension portion from contacting the connecting area between the second folding edge section and the third folding edge section, and avoid the cutting edge from damaging the packaging film at the connecting area, which can further ensure the sealing of the packaging film; the first folding edge section and the second folding edge section are located on the inner side of the third folding edge section. When the folding edge section is bent, the first folding edge section is bent upward first, and then the second folding edge section is bent upward. The length of the first folding edge section and the second folding edge section meets D1≥1mm. This setting can prevent the first folding section from being too long and interfering with the bending of the second folding section, which is conducive to ensuring the convenience of bending the second folding section.
[0008] In an optional embodiment, A distance between an end of a connection area between the first folded edge section and the second folded edge section facing the extension portion and the extension portion is D2, and D2≥1 mm.
[0009] Beneficial effects: This arrangement can ensure the length of the second folding section and the extension length of the second folding section on the third folding section, improve the overall stability of the first folding structure, prevent the second folding section from moving upward, prevent the top of the first folding structure from exceeding the top surface of the battery cell, and prevent the first folding structure from occupying space outside the thickness range of the battery cell, thereby improving the compactness and volume energy density of the battery cell. At the same time, D2≥1mm. This setting can prevent the second folding section from being too long, and prevent the second folding section from abutting the bottom of the first folding section against the extension part when the third folding section is bent, thereby avoiding interference between the connection between the first folding section and the second folding section and the extension part when the third folding section is bent. It is convenient to fold the first folding structure as a whole to the side of the packaging body through the third folding section, and convenient to stick tape on the outer wall surface of the third folding section. The other end of the tape is stuck on the top surface of the battery cell to further fix the first folding structure. D2≥1mm. Such an arrangement can also prevent the second folded edge section from contacting the bottom of the first folded edge section with the extended portion, causing the packaging films to contact and wear each other.
[0010] In an optional embodiment, along the thickness direction of the battery cell, both sides of the packaging film are provided with accommodating grooves, and the electrode group is arranged in the accommodating grooves; it also includes a second folding structure, and the two ends of the second folding structure are respectively connected to the extension part and the third folding section; the first folding structure and the second folding structure are bent back to back.
[0011] Beneficial effect: The sides of the battery cells on the upper and lower sides of the extension part are provided with folded edge structures. When the sides of the battery cells are subjected to force, the upper and lower folded edge structures are subjected to force at the same time to make the force uniform. The two folded edge structures protect the battery cells on the sides of the battery cells, which can improve the safety performance of the battery cells. In order to ensure the volume energy density of the battery cells, it is necessary to ensure that the top of the first folded edge structure does not exceed the top surface of the battery cells. However, when the overall length of the edge sealing area is relatively long, the three folded edge sections of the first folded edge structure are easily bent beyond the top surface of the battery cells. After the second folded edge structure is provided, a part of the longer edge sealing area can be bent opposite to the first folded edge structure to form a second folded edge structure, thereby controlling the overall length of the first folded edge structure and preventing the top surface of the first folded edge structure from exceeding the top surface of the battery cells.
[0012] In an optional embodiment, the second folding structure includes a fourth folding section and a fifth folding section connected in sequence, the fourth folding section is connected to the extension portion, the fifth folding section is connected to the third folding section, and the fifth folding section is arranged in parallel outside the outer wall surface of the fourth folding section.
[0013] In an optional embodiment, the angle between the third folding section and the extension portion is θ, and the angle between the second folding structure and the extension portion is α; 60°≤θ≤120°, and / or, 60°≤α≤120°.
[0014] In an optional embodiment, θ=90°, α=90°; the thickness of the battery cell on the side where the first folded edge structure is located is H1, the thickness of the battery cell on the side where the second folded edge structure is located is H2, and the length of the second folded edge structure is L4, L3≤H1;
[0015] And / or, L4≤H2.
[0016] In an optional embodiment, H2≤H1.
[0017] In an optional embodiment, the distance between the outer wall surface of the third folded edge section and the side surface of the packaging body is W1, the thickness of the packaging film at the edge sealing area is h, and 3h≤W1≤3h+2.
[0018] Beneficial effect: This arrangement can make the first folding structure closer to the side of the packaging body, while avoiding the width of the first folding structure being too wide after folding, which can further ensure the compactness of the battery cell and improve the volume energy density of the battery cell; at the same time, a more compact structure can improve the strength and safety of the first folding structure.
[0019] In an optional implementation, a distance between a side of the second folded edge structure facing the side of the package body and the side of the package body is W2, where W2≥1 mm.
[0020] Beneficial effect: This arrangement can keep the second folded edge structure away from the packaging film in the weak area near the receiving groove, thereby avoiding pulling and damaging the weak area near the receiving groove during folding.
[0021] In a second aspect, the present invention further provides a battery pack, comprising any one of the above-mentioned battery cells. The battery pack comprises the battery cell, has the same technical effect as the battery cell, and will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.
[0023] Figure 1 A side view of a battery cell according to an embodiment of the present invention;
[0024] Figure 2 for Figure 1 A partial enlarged view of the middle A part;
[0025] Figure 3 for Figure 1 A partial enlarged view of the middle A part;
[0026] Figure 4 is a schematic diagram of the warping of the first folding edge section of the first folding edge structure;
[0027] Figure 5 A schematic diagram of an edge sealing area of another battery cell according to an embodiment of the present invention;
[0028] Figure 6 A schematic diagram of an edge sealing area of another battery cell according to an embodiment of the present invention;
[0029] Figure 7 A schematic diagram of an edge sealing area of another battery cell according to an embodiment of the present invention;
[0030] Figure 8FIG. 4 is a side view of another battery cell according to an embodiment of the present invention.
[0031] Description of reference numerals:
[0032] 1. Packaging film; 11. Packaging body; 12. Edge sealing area; 121. Extension portion; 122. First folding structure; 1221. First folding section; 1222. Second folding section; 1223. Third folding section; 123. Second folding structure; 1231. Fourth folding section; 1232. Fifth folding section. DETAILED DESCRIPTION
[0033] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.
[0034] The battery cell in the related art includes a pole group and a packaging film, the packaging film includes a packaging body and a sealing edge area, the packaging body is provided with a receiving groove, the pole group is provided in the receiving groove, and the sealing edge area is located outside the pole group. The outer edge of the sealing edge area is a cutting edge, the packaging area is bent toward the side of the packaging body to form a folded edge, and then the sealing edge area is bent toward the side of the packaging body as a whole, the folded edge is toward the side of the packaging body, and due to the inappropriate bending length of the folded edge, the folded edge is easily deformed and warped after bending, that is, the folded edge will warp toward the side of the packaging body, and the cutting edge is located at the end of the folded edge. After the cutting edge is warped, it is easy to scratch the side of the packaging body or damage the folded edge section adjacent to it, thereby affecting the overall sealing of the packaging film and affecting the safety performance of the battery cell.
[0035] like Figure 1 and Figure 2 As shown, the x direction is called the width direction of the battery cell, the z direction is called the thickness direction of the battery cell, the upper part of the z direction is called the upper part of the battery cell, the lower part of the z direction is called the lower part of the battery cell, the large surface of the battery cell facing upward is its top surface, and the large surface of the battery cell facing downward is its bottom surface.
[0036] Combine the following Figures 1 to 8 , describing an embodiment of the present invention.
[0037] According to an embodiment of the present invention, on the one hand, a battery cell is provided, including an electrode group and a packaging film 1. Among them, the packaging film 1 includes a packaging body 11 and a sealing edge area 12, the packaging body 11 is coated outside the electrode group, the sealing edge area 12 is located outside the electrode group, the sealing edge area 12 includes an extension portion 121 and a first folding structure 122, the extension portion 121 extends toward the outside of the electrode group, and the first folding structure 122 includes a first folding section 1221, a second folding section 1222 and a third folding section 1223 connected in sequence; one end of the third folding section 1223 is connected to the extension portion 121, and the other end is bent relative to the extension portion, the second folding section 1222 is bent inwardly and toward the extension portion 121, the first folding section 1221 is bent away from the extension portion 121, and the two sides of the first folding section 1221 are attached to the inner wall surface of the third folding section 1223 and the outer wall surface of the second folding section 1222; the length of the first folding section 1221 is L1, the length of the second folding section 1222 is L2, and the length of the third folding section 1223 is L3, The distance between one end of the first folding section 1221 away from the extending portion 121 and the connecting area between the second folding section 1222 and the third folding section 1223 is D1, and D1 ≥ 1 mm.
[0038] The first folding structure 122 of the battery cell of this structure includes a first folding section 1221, a second folding section 1222 and a third folding section 1223. The lengths of the first folding section 1221 and the second folding section 1222 satisfy This arrangement can ensure that the first folding section 1221 has a sufficient length, ensure the extension length of the first folding section 1221 on the second folding section 1222, and avoid the first folding section 1221 being too short and warping after folding. Figure 4 The state shown can ensure that the first folding section 1221 is stably and effectively attached to the second folding section 1222. The end of the first folding section 1221 is a cutting edge, which can prevent the cutting edge from damaging the third folding section 1223. At the same time, the first folding section 1221 is located between the second folding section 1222 and the third folding section 1223, so that the cutting edge is away from the side of the package body 11, which can effectively prevent the first folding section 1221 from damaging the side of the package body 11. At the same time, the lengths of the first folding section 1221 and the second folding section 1222 meet D1≥1mm, such a setting can prevent the length of the first folding section 1221 from being too long, prevent the end of the first folding section 1221 away from the extension portion 121 from contacting the connecting area between the second folding section 1222 and the third folding section 1223, avoid the cutting edge from damaging the packaging film 1 at the connecting area, and further ensure the sealing of the packaging film 1; the first folding section 1221 and the second folding section 1222 are located on the inner side of the third folding section 1223, and when the folding sections are bent, the first folding section 1221 is bent upward first, and then the second folding section 1222 is bent upward, and the lengths of the first folding section 1221 and the second folding section 1222 meet D1≥1mm. This arrangement can prevent the first folding section 1221 from being too long and interfering with the bending of the second folding section 1222, which is conducive to ensuring the convenience of bending the second folding section 1222.
[0039] Optionally, in some embodiments, the first folding structure 122 is bent upward.
[0040] If the length of the second folded edge section 1222 is too short, the gap area at the bottom of the second folded edge section 1222 is large, and the overall structure of the first folded edge structure 122 is unstable, causing the second folded edge section 1222 to easily move upward after bending, thereby causing the top of the first folded edge structure 122 to exceed the top surface of the battery cell, which will affect the compactness and volume energy density of the battery cell. In order to avoid this problem, Figure 2 and Figure 3 As shown, in some embodiments, A distance D2 is provided between an end of the connecting area between the first folded edge section 1221 and the second folded edge section 1222 facing the extending portion 121 and the extending portion 121 , and D2 ≥ 1 mm. In this way, the length of the second folded edge section 1222 is ensured, and the extended length of the second folded edge section 1222 on the third folded edge section 1223 is ensured, so as to improve the overall stability of the first folded edge structure 122, prevent the second folded edge section 1222 from moving upward, prevent the top surface of the first folded edge structure 122 from exceeding the top surface of the battery cell, and prevent the first folded edge structure 122 from occupying space outside the thickness range of the battery cell, thereby improving the battery cell degree and volume energy density. At the same time, D2≥1mm. This setting can prevent the connection area between the first folding section 1221 and the second folding section 1222 from abutting the extension portion 121, thereby avoiding interference between the connection between the first folding section 1221 and the second folding section 1222 and the extension portion 121 when bending the third folding section 1223. It is convenient to fold the first folding structure 122 as a whole to the side of the packaging body 11 through the third folding section 1223, and it is convenient to stick tape on the outer wall surface of the third folding section 1223. The other end of the tape is connected to the top surface of the battery cell to further fix the first folding structure 122. D2≥1 mm. This arrangement can also prevent the bottoms of the second folding edge section 1222 and the first folding edge section 1221 from contacting the extension portion 121 and causing the packaging film 1 to contact and wear each other.
[0041] like Figures 1 to 3 As shown, in some embodiments, a first folding structure 122 is provided on one side of the folding line of the packaging film 1, the edge sealing area 12 is located on one side in the thickness direction of the battery cell, and the first folding structure 122 is bent upward.
[0042] In some embodiments, Figures 5 to 7 As shown, both sides of the folding line of the packaging film 1 of the battery cell are provided with accommodating grooves, and the electrode group is arranged in the accommodating grooves; the battery cell also includes a second folding structure 123, and the two ends of the second folding structure 123 are respectively connected to the extension part 121 and the third folding section 1223; the first folding structure 122 and the second folding structure 123 are bent back to back. The side surfaces of the battery cell on the upper and lower sides of the extension part 121 are provided with folding structures. When the side surface of the battery cell is subjected to force, the upper and lower folding structures are subjected to force at the same time to make the force uniform. The two folding structures protect the battery cell on the side surface of the battery cell, which can improve the safety performance of the battery cell. In order to ensure the volume energy density of the battery cell, it is necessary to ensure that the top of the first folding structure 122 does not exceed the top surface of the battery cell. However, when the overall length of the edge sealing area 12 is long, the three folding sections of the first folding structure 122 are easy to exceed the top surface of the battery cell after being bent. After the second folding structure 123 is set, a part of the longer edge sealing area 12 can be bent away from the first folding structure 122 to form the second folding structure 123, so as to control the overall length of the first folding structure 122 and prevent the top surface of the first folding structure 122 from exceeding the top surface of the battery cell.
[0043] In some embodiments, Figures 5 to 7 As shown, the second folding structure 123 includes a fourth folding section 1231 and a fifth folding section 1232 connected in sequence, the fourth folding section 1231 is connected to the extension portion 121, the fifth folding section 1232 is connected to the third folding section 1223, and the fifth folding section 1232 is arranged in parallel outside the outer wall surface of the fourth folding section 1231. The second folding structure 123 includes two folding sections arranged in parallel, which can protect the battery cell from the side; at the same time, the second folding structure 123 has a small number of bends, which can reduce the space occupied by the second folding structure 123 in the width direction of the battery cell, so as to further improve the volume energy density of the battery cell.
[0044] The extension portion 121 is roughly parallel to the large surface of the battery cell. In some embodiments, such as the angle between the third folding section 1223 and the extension portion 121 is θ, the angle between the second folding structure 123 and the extension portion 121 is α; 60°≤θ≤120°, and / or, 60°≤α≤120°. That is, the first folding structure 122 is inclined or vertically arranged relative to the extension portion 121, and the second folding structure 123 is inclined or vertically arranged relative to the extension portion 121. When the first folding structure 122 and the second folding structure 123 are inclined, the inclination angle satisfies 60°≤θ≤120°, 60°≤α≤120°, that is, the inclination angle of the folding structure is moderate, which can prevent the first folding structure 122 and the second folding structure 123 from having too large an inclination angle and occupying too much space in the width direction of the battery cell.
[0045] Optionally, in some embodiments, θ=90°, α=90°, that is, the first folding structure 122 and the second folding structure 123 are both arranged vertically relative to the extension portion 121, and the first folding structure 122 and the second folding structure 123 are parallel to the side of the pole group, and the folding structure occupies the smallest space in the width direction of the battery cell, which can further improve the compactness and volume energy density of the battery cell structure. The thickness of the battery cell on the side where the first folding structure 122 is located is H1, and the thickness of the battery cell on the side where the second folding structure 123 is located is H2, L3≤H1, that is, the top surface of the first folding structure 122 does not exceed the top surface of the battery cell, which can ensure the compactness and volume energy density of the battery cell.
[0046] In some embodiments, the length of the second folded edge structure 123 is L4, L4≤H2, and the bottom surface of the second folded edge structure 123 does not exceed the bottom surface of the battery cell. This arrangement can further improve the compactness and volume energy density of the battery cell.
[0047] In some embodiments, Figure 6 As shown, the first folding structure 122 is bent toward the first thickness direction (the upper part of the battery cell), and the second folding structure 123 is bent toward the second thickness direction (i.e., the lower part of the battery cell), H2≤H1, that is, the thickness of the upper battery cell is greater than or equal to the thickness of the lower battery cell. This arrangement can make the thickness of the battery cells on both sides of the extension part 121 the same, or make the thickness of the battery cell on one side greater than the thickness of the battery cell on the other side. This arrangement allows the battery cell to have sufficient thickness in one of the two thicknesses in the thickness direction, so that the longer folding structure can be bent toward the side with the thicker thickness of the battery cell, thereby preventing the end of the folding structure from exceeding the large surface of the battery cell.
[0048] In some embodiments, Figure 6As shown, the fifth folding edge section 1232 is attached to the outer wall surface of the fourth folding edge section 1231, the fifth folding edge section 1232 is flush with the third folding edge section 1223, and the first folding edge section 1221 and the second folding edge section 1222 are located on the inner side of the fifth folding edge section 1232. This arrangement can improve the overall strength of the second folding edge structure 123, ensure its protective effect on the battery cell, and at the same time make the two folding edge structures closer to the side of the package body 11, which is conducive to improving the compactness of the battery cell.
[0049] In other embodiments, Figure 7 As shown, the fifth folding edge section 1232 is arranged in parallel with the fourth folding edge section 1231 and spaced apart from each other.
[0050] In some embodiments, the distance between the outer wall surface of the third folding section 1223 and the side surface of the package body 11 is W1, the thickness of the package film 1 at the edge sealing area 12 is h (the thickness of the two layers of package film 1 after hot pressing), 3h≤W1≤3h+2. This arrangement can make the first folding structure 122 closer to the side surface of the package body 11, while avoiding the width of the first folding structure 122 after folding being too wide, which can further ensure the compactness of the battery cell and improve the volume energy density of the battery cell; at the same time, a more compact structure can improve the strength and safety of the first folding structure 122.
[0051] In some embodiments, the distance between the side of the second folding structure 123 facing the side of the package body 11 and the side of the package body 11 is W2, W2 ≥ 1mm. The receiving groove is formed by stamping, and the strength of the packaging film 1 in the area near the receiving groove is weak, W2 ≥ 1mm. This arrangement can keep the second folding structure 123 away from the packaging film 1 near the receiving groove, avoiding pulling the weak area near the receiving groove when folding.
[0052] like Figure 8 In the embodiment, when the accommodating grooves are provided on both sides, the first folding structure 122 may also be provided only on the upper part or the lower part of the battery cell.
[0053] According to an embodiment of the present invention, on the other hand, a battery pack is provided, comprising the above-mentioned battery cell.
[0054] In the battery pack of this structure, the first folding structure 122 of the battery cell therein includes a first folding section 1221, a second folding section 1222 and a third folding section 1223, and meets D1≥1mm ，Such a configuration can ensure that the first folding section 1221 has sufficient length, ensure the extension length of the first folding section 1221 on the second folding section 1222, ensure that the first folding section 1221 is stably and effectively fitted on the second folding section 1222, and prevent the cutting edge from damaging the third folding section 1223; at the same time, the first folding section 1221 is located between the second folding section 1222 and the third folding section 1223, so that the cutting edge is away from the side of the packaging body 11, preventing the first folding structure 122 from damaging the side of the packaging body 11. It can also prevent the length of the first folding section 1221 from being too long, and prevent the end of the first folding section 1221 away from the extension portion 121 from contacting the connecting area between the second folding section 1222 and the third folding section 1223, thereby preventing the cutting edge from damaging the packaging film 1 at the connecting area, and further ensuring the sealing of the packaging film 1; in addition, it can also prevent the length of the first folding section 1221 from being too long and interfering with the bending of the second folding section 1222, which is conducive to ensuring the convenience of bending the second folding section 1222.
[0055] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations are all within the scope defined by the appended claims.
Claims
1. A battery cell, characterized in that: include: Pole group; A packaging film comprises a packaging body and an edge sealing area, wherein the packaging body is coated on the outside of the electrode group, the edge sealing area is located outside the electrode group, the edge sealing area comprises an extension portion and a first folding structure, the extension portion extends toward the outside of the electrode group, the first folding structure comprises a first folding section, a second folding section and a third folding section connected in sequence; one end of the third folding section is connected to the extension portion, and the other end is bent relative to the extension portion, the second folding section is bent inwardly and toward the extension portion, the first folding section is bent away from the extension portion, and the two sides of the first folding section are attached to the inner wall surface of the third folding section and the outer wall surface of the second folding section; the length of the first folding section is L1, the length of the second folding section is L2, and the length of the third folding section is L3, The distance between the connecting area of the second folding section of the first folding section and the third folding section is D1, and D1≥1mm.
2. The battery cell according to claim 1, characterized in that: A distance between an end of a connection area between the first folded edge section and the second folded edge section facing the extension portion and the extension portion is D2, and D2≥1 mm.
3. The battery cell according to claim 1 or 2, characterized in that: Along the thickness direction of the battery cell, both sides of the packaging film are provided with accommodating grooves, and the electrode group is arranged in the accommodating grooves; it also includes a second folding structure, and the two ends of the second folding structure are respectively connected to the extension part and the third folding section; the first folding structure and the second folding structure are bent back to back.
4. The battery cell according to claim 3, characterized in that: The second folding structure includes a fourth folding section and a fifth folding section connected in sequence, the fourth folding section is connected to the extension portion, the fifth folding section is connected to the third folding section, and the fifth folding section is arranged in parallel outside the outer wall surface of the fourth folding section.
5. The battery cell according to claim 3, characterized in that: The angle between the third folding section and the extension portion is θ, and the angle between the second folding structure and the extension portion is α; 60°≤θ≤120°, and / or, 60°≤α≤120°.
6. The battery cell according to claim 5, characterized in that: θ=90°, α=90°; the thickness of the battery cell on the side where the first folded edge structure is located is H1, the thickness of the battery cell on the side where the second folded edge structure is located is H2, and the length of the second folded edge structure is L4, L3≤H1; And / or, L4≤H2.
7. The battery cell according to claim 6, characterized in that: H2≤H1.
8. The battery cell according to claim 6, characterized in that: The distance between the outer wall surface of the third folded edge section and the side surface of the packaging body is W1, and the thickness of the packaging film at the edge sealing area is h, 3h≤W1≤3h+2.
9. The battery cell according to claim 6, characterized in that: A distance between a side of the second folded edge structure facing the side of the package body and the side of the package body is W2, and W2≥1 mm.
10. A battery pack, characterized in that: A battery cell comprising the battery cell according to any one of claims 1 to 9.