Secondary battery and preparation method therefor, and electronic device

Abstract

The present application relates to a secondary battery and a preparation method therefor, and an electronic device. The secondary battery comprises a packaging bag, an electrode assembly and tabs, wherein the electrode assembly is accommodated in the packaging bag; the packaging bag has a top sealing edge; one end of each tab is electrically connected to the electrode assembly within the packaging bag, and the other end thereof extends out of the packaging bag from the top sealing edge; and the top sealing edge comprises a straight part and a zigzag part that are connected to each other, the tabs extending out of the packaging bag from the straight part. In the direction of the thickness of the secondary battery, the zigzag part has a first surface and a second surface that are arranged opposite each other, the first surface having a first recessed region recessed towards the second surface, and the first recessed region enabling the second surface to form a first protrusion. The secondary battery in the present application has relatively high packaging strength, so that the possibility of the packaging bag being burst open can be reduced; in addition, the packaging width thereof is smaller, which can better meet the ultra-thin and miniaturized design requirements of the secondary battery.

Description

Secondary battery and preparation method thereof, and electronic device Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a secondary battery and a preparation method thereof, and an electronic device. Background Art

[0002] As electronic products advance in technology, they are increasingly pursuing thinner and lighter designs. For example, tablets, mobile phones, and e-books are becoming mainstream, with long battery life and lightweight designs becoming increasingly mainstream. Secondary batteries, the power source of these electronic products, require a high electrolyte retention capacity to meet these demands. However, during a collision, the electrolyte within the secondary battery can easily break the battery seal, causing it to fail.

[0003] Summary of the Invention

[0004] The purpose of the present application is to provide a secondary battery and a preparation method thereof, and an electronic device, aiming to improve the problem that the seal of the secondary battery is easily broken.

[0005] In a first aspect, the present application provides a secondary battery comprising a packaging bag, an electrode assembly, and a tab. The electrode assembly is housed within the packaging bag, which has a top seal. One end of the tab is electrically connected to the electrode assembly within the packaging bag, and the other end extends from the top seal outside the packaging bag. The top seal includes a straight portion and a curved portion connected thereto, and the tab extends from the straight portion outside the packaging bag. Along the thickness direction of the secondary battery, the curved portion has a first surface and a second surface disposed opposite each other. The first surface has a first recessed region that is recessed toward the second surface, and the first recessed region forms a first raised portion on the second surface.

[0006] In the above technical solution, by configuring the zigzag portion of the top seal as a concave-convex zigzag structure, compared to a flat package, under conditions of equal package width, the concave-convex zigzag structure can increase the package area, thereby improving the packaging strength of the packaging bag and effectively reducing the risk of the top seal being broken open. Alternatively, for a flat package, under conditions of equal packaging strength, the width of the concave-convex zigzag package structure is smaller, thereby reducing the length of the secondary battery and facilitating the miniaturization of the secondary battery design. For the protruding portion of the tab, a flat package is adopted, that is, the tab extends from the straight portion, which can reduce the tab's interference with the hot pressing packaging process. At the same time, the tab itself is a flat structure, which is more conducive to the adhesion of the first and second sealing layers to the tab, thereby improving the packaging strength. The zigzag design of multiple raised portions and recessed areas further enhances the packaging strength of the top seal.

[0007] In some preferred embodiments, the zigzag portion includes at least two first raised portions. The at least two first raised portions are spaced apart along the length of the secondary battery, with a second recessed area formed between adjacent first raised portions. The second recessed area forms a second raised portion on the first surface. The tab extends out of the packaging bag along the length of the secondary battery.

[0008] In some preferred embodiments, the first raised portion and the second recessed portion are connected by an arc-shaped chamfer. The arc-shaped chamfer provides a smooth transition between the raised and recessed portions. This not only reduces the accumulation of dust and impurities at the joint, but also helps disperse stress, reducing tearing of the top seal and thereby improving the packaging strength of the top seal.

[0009] Optionally, the radius of the arc chamfer is R, 0.4 mm ≤ R ≤ 0.8 mm.

[0010] In some preferred embodiments, along the width direction of the secondary battery, the secondary battery further has a first side seal and a second side seal that are relatively arranged; along the thickness direction of the first side seal, the first side seal includes a third surface and a fourth surface that are relatively arranged, and the third surface has a third recessed area recessed toward the fourth surface, and the third recessed area forms a third raised portion on the fourth surface; by setting the first side seal to be concave and convex, the packaging area of ​​the first side seal can be increased and the packaging strength can be improved.

[0011] Along the thickness direction of the second side seal, the second side seal includes a fifth surface and a sixth surface disposed opposite each other. The fifth surface has a fourth recessed area that is recessed toward the sixth surface. The fourth recessed area forms a fourth raised portion on the sixth surface. By creating a concave-convex zigzag pattern on the second side seal, the sealing area of ​​the second side seal is increased, thereby enhancing the sealing strength of the packaging bag.

[0012] In some preferred embodiments, the secondary battery has a first wall portion and a second wall portion disposed opposite each other along its width. The first side seal is disposed on the first wall portion and folded toward the first wall portion, thereby reducing the effect of the second side seal on the width of the secondary battery. The second side seal is disposed on the second wall portion and folded toward the second wall portion, thereby reducing the effect of the second side seal on the width of the secondary battery.

[0013] In some preferred embodiments, the first side seal includes a first portion and a second portion, wherein the first portion is connected between the first wall portion and the second portion, the first portion is folded toward the first wall portion, and the second portion is folded toward the first portion. After multiple folds, the width of the first side seal can be reduced, thereby reducing the impact of the first side seal on the thickness of the secondary battery, thereby facilitating the ultra-thin design requirements of the secondary battery.

[0014] In some preferred embodiments, the second portion is located between the first portion and the first wall portion along the width direction of the secondary battery, which can effectively prevent the second portion from warping outside the secondary battery.

[0015] In some preferred embodiments, the first side seal includes at least two third raised portions, which are spaced apart from each other, with a fifth recessed area formed between adjacent third raised portions. The fifth recessed area forms a fifth raised portion on the third surface. The fourth surface of the second portion is disposed facing the fourth surface of the first portion, and the third raised portion on the second portion is at least partially disposed within the fifth recessed area on the first portion. By embedding the third raised portion within the fifth recessed area, the thickness of the folded first side seal can be reduced. This not only reduces the impact of the first side seal on the thickness of the secondary battery, but also reduces the impact of the first side seal on the width of the secondary battery, thereby meeting the requirements for ultra-thin and miniaturized secondary battery designs.

[0016] In some preferred embodiments, along the thickness direction of the secondary battery, the secondary battery has a first main surface and a second main surface arranged opposite to each other; the first portion has a first end and a second end arranged opposite to each other, the first end is connected to the first wall portion, and the second end is connected to the second portion. Along the thickness direction of the secondary battery, the height from the first end to the first main surface is H1, the height from the first end to the second main surface is H2, and the height from the first end to the second end is H 3。 H3≤H1, and / or H3≤H2. After folding, the first portion does not exceed the first main surface and the second main surface, which can reduce the impact of the first side seal on the thickness of the secondary battery.

[0017] In some preferred embodiments, the thickness of the secondary battery is T along the thickness direction, where T is ≤ 2.6 mm. After folding, the widths of the first and second side seals are relatively small, having little impact on the width of the secondary battery. Therefore, the thickness of the secondary battery can be adaptively reduced, facilitating the miniaturization and ultra-thin design requirements of the secondary battery.

[0018] In some preferred embodiments, along the thickness direction of the secondary battery, the top seal includes a first sealing portion and a second sealing portion disposed opposite each other, with the tab disposed between the first and second sealing portions, and the first and second sealing portions are bonded together. In a straight portion, the peel strength between the first and second sealing portions is G1, G1 ≥ 1 N / mm; and / or, in a curved portion, the peel strength between the first and second sealing portions is G2, G2 ≥ 1.875 N / mm. This provides the top seal with a high packaging strength and reduces the risk of the top seal being broken open.

[0019] In some preferred embodiments, the first sealing portion includes a first protective layer, a first sealing layer, and a first metal layer disposed between the first protective layer and the first sealing layer. The second sealing portion includes a second protective layer, a second sealing layer, and a second metal layer disposed between the second protective layer and the second sealing layer. The first sealing layer and the second sealing layer are bonded together.

[0020] In some preferred embodiments, along the length direction of the secondary battery, the bonding width between the first sealing portion and the second sealing portion is W, where W is ≥ 0.8 mm.

[0021] In a second aspect, the present application further proposes a method for preparing a secondary battery as described in any embodiment of the first aspect, comprising:

[0022] A head is provided, the head comprising a first head and a second head, the first head having a convex section and a first straight section, the second head having a concave section and a second straight section;

[0023] Providing a packaging bag, wherein the packaging bag has a top seal, and the tabs of the secondary battery extend out of the packaging bag from the top seal;

[0024] Place the first head and the second head on both sides of the top seal thickness direction, wherein the convex section of the first head is opposite to the concave section of the second head, the first straight section of the first head is opposite to the second straight section of the second head, and the tab is located between the first straight section and the second straight section;

[0025] The first and second sealing heads are heat-pressed to seal the top edges and the top edges are bonded and sealed.

[0026] In a third aspect, an embodiment of the present application further provides an electronic device comprising the secondary battery as described in any embodiment of the first aspect above.

[0027] Additional aspects and advantages of the embodiments of the present application will be described, shown, or explained in part in the following description through implementation of the embodiments of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] One or more embodiments are exemplarily described by corresponding drawings, which do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings are represented as similar elements, and unless otherwise stated, the dimensions in the drawings do not constitute proportional limitations.

[0029] FIG1 shows a schematic structural diagram of a secondary battery according to one embodiment of the present application;

[0030] FIG2 shows an exploded schematic diagram of a secondary battery according to one embodiment of the present application;

[0031] FIG3 shows a schematic diagram of the structure of each layer of the first bag body and the second bag body according to one embodiment of the present application;

[0032] FIG4 shows a schematic diagram of the installation of a secondary battery according to one embodiment of the present application;

[0033] FIG5 shows a schematic structural diagram of a top edge seal according to one embodiment of the present application;

[0034] FIG6 shows a schematic structural diagram of a top edge seal according to one embodiment of the present application;

[0035] FIG7 shows a schematic diagram of a top edge sealing hot pressing package according to one embodiment of the present application;

[0036] FIG8 shows a schematic structural diagram of a top edge seal according to one embodiment of the present application;

[0037] FIG9 shows a schematic structural diagram of a top edge seal according to one embodiment of the present application;

[0038] FIG10 shows a schematic structural diagram of a secondary battery according to one embodiment of the present application (viewed along a third direction Z);

[0039] FIG11 shows a schematic structural diagram of a first side edge seal according to one embodiment of the present application;

[0040] FIG12 shows a schematic structural diagram of a secondary battery according to one embodiment of the present application (viewed along a first direction X);

[0041] FIG13 is a schematic diagram showing a partial structure of a secondary battery according to one embodiment of the present application (viewed along a first direction X);

[0042] FIG14 is a schematic diagram showing a partial structure of a secondary battery according to one embodiment of the present application (viewed along a first direction X);

[0043] FIG15 shows a schematic structural diagram of a first side edge seal according to one embodiment of the present application;

[0044] DESCRIPTION OF THE REFERENCE NUMERALS: 100, secondary battery; 10, packaging bag; 11, first bag body; 11a, first sealing layer; 11b, first metal layer; 11c, first protective layer; 111, first cavity; 12, second bag body; 12a, second sealing layer; 12b, second metal layer; 12c, second protective layer; 121, second cavity; 13, top seal; 13a, first sealing portion; 13b, second sealing portion; 131, straight portion; 132, curved portion; 1321, first surface; 1322, second surface; 1323, first recessed area; 1324, first raised portion; 1324a, top portion; 1325, second recessed area; 1326, second raised portion; 133, curved chamfer; 14. First side seal; 14a. First portion; 14a1. First end portion; 14a2. Second end portion; 14b. Second portion; 141. Third surface; 142. Fourth surface; 143. Third recessed area; 144. Third raised portion; 145. Fifth recessed area; 146. Fifth raised portion; 15. Second side seal; 16. First wall portion; 17. Second wall portion; 18. First main surface; 19. Second main surface; 20. Electrode assembly; 30. Tab; 31. Positive tab; 32. Negative tab; 200. First end cap; 210. Raised section; 220. First straight section; 300. Second end cap; 310. Recessed section; 320. Second straight section; X, first direction; Y, second direction; Z, third direction. DETAILED DESCRIPTION

[0045] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly described below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments.

[0046] References to "embodiments" in this application mean that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments.

[0047] In the description of the embodiments of this application, the technical terms "first" and "second" are used only to distinguish different objects and should not be understood to indicate or imply relative importance or implicitly specify the quantity, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, the meaning of "plurality" is more than two, unless otherwise clearly and specifically defined.

[0048] In the description of the embodiments of this application, the term "and / or" is simply a description of the association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent the following three situations: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0049] Next, the terms "upper", "lower", "top", "bottom", etc. used below to indicate directions or positional relationships are all relative to the first direction X. The technical features involved in the different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0050] First, the present application proposes a secondary battery 100. Figures 1 and 2 respectively show the structure and explosion structure of the secondary battery 100 provided in one embodiment of the present application. The secondary battery 100 includes a packaging bag 10, an electrode assembly 20 and a tab 30. The electrode assembly 20 is accommodated in the packaging bag 10. The packaging bag 10 has a top seal 13. One end of the tab 30 is electrically connected to the electrode assembly 20 in the packaging bag 10, and the other end extends out of the packaging bag 10 from the top seal 13.

[0051] Regarding the above-mentioned packaging bag 10, the packaging bag 10 serves as a mounting base, a container and an outer protective structure, which defines a receiving space (not shown in the figure), which can be used to accommodate the electrolyte (not shown in the figure) and the above-mentioned electrode assembly 20.

[0052] For example, referring to Figures 1 and 2, the packaging bag 10 includes a first bag body 11 and a second bag body 12, the first bag body 11 having a first pit cavity 111, and the second bag body 12 having a second pit cavity 121. The electrode assembly 20 can be first placed in the first pit cavity 111, and the second bag body 12 and the first bag body 11 are arranged relative to each other along the thickness direction (third direction Z) of the secondary battery 100, and the second bag body 12 covers the first pit cavity 111. The first pit cavity 111 and the second pit cavity 121 are connected to form a storage space. The edges of the two bag bodies can be bonded to each other by hot pressing the connection between the edges of the two bag bodies, thereby forming a complete packaging bag 10 to seal the storage space. Among them, after the edges of the two bag bodies are bonded to each other, a sealing edge structure is formed on the outside of the packaging bag 10. In the embodiment of the present application, the sealing edge structure includes a top sealing edge 13, a first side sealing edge 14 and a second side sealing edge 15; in some other embodiments, it may also include a bottom sealing edge, etc.

[0053] Optionally, further referring to FIG. 3 , the first bag body 11 includes a first sealing layer 11a, a first protective layer 11c, and a first metal layer 11b disposed between the first sealing layer 11a and the first protective layer 11c; the second bag body 12 includes a second sealing layer 12a, a second protective layer 12c, and a second metal layer 12b disposed between the second sealing layer 12a and the second protective layer 12c. The first sealing layer 11a and the second sealing layer 12a are disposed opposite each other in a third direction Z. When the edges of the two bags are heat-pressed, the first sealing layer 11a and the second sealing layer 12a are bonded.

[0054] The first sealing layer 11a and the second sealing layer 12a can both be made of polypropylene, polyethylene, or polyester. For example, the first sealing layer 11a and the second sealing layer 12a are both made of polypropylene, which has good corrosion resistance and can isolate the electrolyte from the first metal layer 11b and the second metal layer 12b, thereby ensuring the chemical stability of the packaging bag 10.

[0055] The first metal layer 11b and the second metal layer 12b can effectively reduce the penetration of moisture from the air into the storage space, and provide the packaging bag 10 with a certain strength, thereby reducing damage to the packaging bag 10. The first metal layer 11b and the second metal layer 12b can both be made of metals such as aluminum, stainless steel, aluminum-titanium alloy, or copper. For example, using aluminum-plastic film as the material for the packaging bag 10 has excellent ductility and formability, facilitating the punching of the first cavity 111 and the second cavity 121, as well as facilitating the heat-pressing packaging of the edge sealing.

[0056] The first protective layer 11c and the second protective layer 12c serve as the outermost layers of the packaging bag 10 and can be made of polyamide, polyester, polypropylene, polyethylene or polyvinyl chloride, etc., which can effectively reduce the penetration of external air or moisture into the containing space, and at the same time enable the first metal layer 11b and the second metal layer 12b to have better deformation ability.

[0057] Referring to Figures 1 and 2 , the electrode assembly 20 is housed within the packaging bag 10. The electrode assembly 20 includes a positive electrode sheet (not shown), a separator (not shown), and a negative electrode sheet (not shown). The positive electrode sheets, separator, and negative electrode sheet are alternately stacked or stacked and wound. Electrolyte infiltrates the electrode assembly 20 within the storage space, generating an electrochemical reaction with the electrode assembly 20 to achieve charge and discharge of the secondary battery 100.

[0058] The tabs 30 can be made of a metal such as aluminum, copper, or nickel, which has good electrical and thermal conductivity. The tabs 30 include a positive tab 31 and a negative tab 32. The positive tab 31 is electrically connected to the positive electrode sheet to lead out the positive electrode, and the negative tab 32 is electrically connected to the negative electrode sheet to lead out the negative electrode.

[0059] Please refer to Figures 2 and 4. The tab 30 can adopt a flat structure. One end of the tab 30 is electrically connected to the electrode assembly 20 in the accommodation space. The electrical connection method includes but is not limited to welding, clamping or conductive adhesive bonding. The other end of the tab 30 extends out of the packaging bag 10 for electrical connection to an external circuit.

[0060] For example, the top seal 13 includes a first seal portion 13a and a second seal portion 13b. The first seal portion 13a is part of the first bag body 11, and the second seal portion 13b is part of the second bag body 12. Before the top seal 13 of the packaging bag 10 is hot-pressed, the tab 30 is disposed between the first seal portion 13a and the second seal portion 13b. One end of the tab 30 is electrically connected to the electrode assembly 20, and the other end extends beyond the first seal portion 13a and the second seal portion 13b. After hot-pressing, the tab 30 is bonded and fixed between the first seal portion 13a and the second seal portion 13b.

[0061] In the embodiment of the present application, the top seal 13 is provided with a connected straight portion 131 and a curved portion 132. Referring to Figures 5 and 6, the tab 30 extends from the straight portion 131. Along the thickness direction of the secondary battery 100 (the third direction Z), the curved portion 132 has a first surface 1321 and a second surface 1322 that are oppositely disposed. The first surface 1321 has a first recessed area 1323 that is recessed toward the second surface 1322. When viewed along the third direction Z, the first recessed area 1323 forms a first protrusion 1324 on the second surface 1322.

[0062] Optionally, in some embodiments, along the length direction of the secondary battery 100 (the first direction X, the direction in which the tab 30 extends is usually regarded as the length direction of the secondary battery 100), the bonding width between the first sealing portion 13a and the second sealing portion 13b is W, that is, the packaging width of the top sealing edge 13 is W, W≥0.8mm. Compared with the flat package, at the same width, the tortuous package with concave and convex settings has a larger packaging area and higher packaging strength; therefore, the width of the top sealing edge 13 can be adaptively reduced to meet the miniaturization design of the secondary battery 100. Regarding the packaging strength, in the straight part 131, the peeling strength (i.e., the packaging strength) between the first sealing part 13a and the second sealing part 13b is G1, G1 ≥ 1N / mm; and / or, in the curved part 132, the peeling strength between the first sealing part 13a and the second sealing part 13b is G2, G2 ≥ 1.875N / mm, so that the top sealing edge 13 has a higher packaging strength, reducing the top sealing edge 13 from being broken open.

[0063] Regarding the shape of the top seal 13, a seal with concave and convex portions can be used. For example, referring to FIG7 , the seal includes a first seal 200 and a second seal 300. The first seal 200 has a raised section 210 and a first straight section 220, while the second seal 300 has a recessed section 310 and a second straight section 320. The first seal 200 and the second seal 300 are respectively placed on either side of the thickness direction (third direction Z) of the top seal 13. The raised section 210 of the first seal 200 and the recessed section 310 of the second seal 300 are opposite each other. After hot pressing, a first recessed area 1323 is formed on the first surface 1321, and a first raised portion 1324 is formed on the second surface 1322. Furthermore, the first straight section 220 of the first seal 200 and the second straight section 320 of the second seal 300 are opposite each other, and the tab 30 is located between the first straight section 220 and the second straight section 320.

[0064] Optionally, the first head 200 may also have a recessed section 310, and the second head 300 may have a raised section 210; or both the first head 200 and the second head 300 may have a recessed section 310 and a raised section 210, to ensure that the raised section 210 or the recessed section 310 of the first head 200 can be crimped with the raised section 210 or the recessed section 310 of the second head 300.

[0065] By configuring the zigzag portion 132 of the top seal 13 as a concave-convex zigzag structure, compared to a flat package, under conditions of equal package width, the concave-convex zigzag structure can increase the package area, thereby improving the package strength of the packaging bag 10 and reducing the risk of electrolyte within the packaging bag 10 breaking through the top seal 13. Alternatively, compared to a flat package, under conditions of equal package strength, the width of the concave-convex zigzag package structure is smaller, thereby reducing the length of the secondary battery 100 and facilitating the miniaturization of the secondary battery 100. Regarding the portion of the tab 30 that extends outward, in the embodiment of the present application, a flat package is employed, whereby the tab 30 extends outward from the flat portion 131. This reduces interference of the tab 30 with the hot pressing process. Furthermore, the tab 30 itself is a flat structure, which further facilitates adhesion between the first sealing layer 11a, the second sealing layer 12a, and the tab 30, thereby improving package strength.

[0066] Since the tab 30 includes a positive tab 31 and a negative tab 32, two straight portions 131 may be provided. Referring to FIG5 , along the width direction (second direction Y) of the secondary battery 100, the top sealing edge 13 includes a curved portion 132, a straight portion 131, a curved portion 132, a straight portion 131, and a curved portion 132, which are sequentially provided. A straight portion 131 is provided between two adjacent curved portions 132 to facilitate the extension of the positive tab 31 and the negative electrode sheet.

[0067] In some other embodiments, when the secondary battery 100 adopts a multi-tab 30 structure, the top sealing plate may also be provided with multiple straight portions 131 to ensure that each tab 30 can extend out of the packaging bag 10 from the straight portion 131 .

[0068] Please refer to Figure 8. In some embodiments, the curved portion 132 includes at least two first protrusions 1324. Along the length direction of the secondary battery 100 (the first direction X, usually the direction in which the tab 30 extends is regarded as the length direction of the secondary battery 100), the at least two first protrusions 1324 are arranged at intervals from each other, and a second recessed area 1325 is formed between two adjacent first protrusions 1324. The second recessed area 1325 causes the first surface 1321 to form a second protrusion 1326.

[0069] Taking two first protrusions 1324 as an example, the first surface 1321 has two first recessed areas 1323 spaced apart from each other. The two first recessed areas 1323 are recessed toward the second surface 1322, resulting in two first protrusions 1324 on the second surface 1322. When viewed along the first direction Z, the two first protrusions 1324 are spaced apart, forming a second recessed area 1325 between the two first protrusions 1324. The second recessed area 1325 then forms a second protrusion 1326 on the first surface 1321. The zigzag design of multiple protrusions and recessed areas further enhances the packaging strength of the top sealing edge 13. In other embodiments, the number of first protrusions 1324 may also be three, four, or five.

[0070] Optionally, at least two first protrusions 1324 may also be arranged at intervals along the width direction (second direction Y) of the secondary battery 100. Referring to Figure 9, the top seal 13 is arranged in a concave and convex manner along the width direction (second direction Y) of the secondary battery 100, which can also increase the packaging area of ​​the top seal 13 and improve the sealing strength. In some other embodiments, at least two first protrusions 1324 may also be arranged in other directions, which can also increase the packaging area. The shape of the top seal 13 can be changed by changing the shape of the head to ensure that it has a recessed area and a protruding portion.

[0071] Referring to Figure 8 , the first raised portion 1324 and the second recessed area 1325 are connected by a curved chamfer 133. This creates a smooth transition between the raised and recessed portions, reducing the accumulation of dust and impurities at the joint. Furthermore, the curved chamfer 133 helps disperse stress, reducing tearing of the top seal 13 and thereby improving the packaging strength of the top seal 13. For example, the radius of the curved chamfer 133 is R, with a range of 0.4 mm ≤ R ≤ 0.8 mm, ensuring a smooth transition between the first raised portion 1324 and the second recessed area 1325.

[0072] Similarly, the first protrusion 1324 has a top 1324 a away from the first surface 1321 . The top 1324 a may also be provided with an arc chamfer 133 to reduce stress concentration at the top 1324 a of the first protrusion 1324 and improve the packaging strength there.

[0073] Referring to Figure 10 , along the width direction of the second battery (second direction Y), the secondary battery 100 has a first side seal 14 and a second side seal 15 that are oppositely disposed. The first side seal 14 and the second side seal 15 can be configured similarly to the top seal 13. The difference is that the first side seal 14 and the second side seal 15 do not need to extend beyond the tab 30, and therefore, do not need to have a straight portion 131. The package width of the first side seal 14 and the second side seal 15 can also be set to be greater than 0.8 mm.

[0074] Further referring to Figure 11 , along the thickness direction of the first side seal 14 , the first side seal 14 includes a third surface 141 and a fourth surface 142 disposed opposite each other. The third surface 141 has a third recessed area 143 , which is recessed toward the fourth surface 142 , forming a third raised portion 144 on the fourth surface 142 . By zigzagging the first side seal 14 in a concave-convex manner, the packaging area of ​​the first side seal 14 can be increased, thereby enhancing the packaging strength. It should be noted that the first side seal 14 is typically a flat structure. When unfolded, the thickness direction of the first side seal 14 is generally aligned with the thickness direction of the secondary battery 100 . After folding, the first side seal 14 may have multiple thickness directions, each of which is determined based on the flatness of the first side seal 14 .

[0075] Along the thickness direction of the second side seal 15, the second side seal 15 includes a fifth surface (not shown in the figure; the structure of the second side seal 15 is similar to that of the first side seal 14, and for details, please refer to the relevant structure of the first side seal 14) and a sixth surface (not shown in the figure). The fifth surface has a fourth recessed area (not shown in the figure), which is recessed toward the sixth surface, forming a fourth raised portion (not shown in the figure). By arranging the second side seal 15 in a concave and convex manner, the packaging area of ​​the second side seal 15 can be increased, thereby improving the packaging strength of the packaging bag 100.

[0076] Optionally, multiple third protrusions 144 may be provided, spaced apart along the width direction (second direction Y) of the secondary battery 100. A fifth recessed area 145 is formed between adjacent third protrusions 144. The fifth recessed area 145 forms a fifth protrusion 146 on the third surface 141. This multi-layered concave-convex structure further enhances the sealing strength of the first side seal 14. Similarly, multiple fourth protrusions may be provided to enhance the sealing strength of the second side seal 15.

[0077] The second protrusion 1326 , the third protrusion 144 , the fourth protrusion and the fifth protrusion 146 can be configured similarly to the first protrusion 1324 , for example, connected to each recessed area via an arc chamfer 133 to disperse stress and improve the packaging strength of the packaging bag 10 .

[0078] Referring to Figures 10 and 12 , in some embodiments, the secondary battery 100 has a first wall portion 16 and a second wall portion 17 disposed opposite each other along the width direction (second direction Y) of the secondary battery 100. A first side seal 14 is disposed on the first wall portion 16 and folded toward the first wall portion 16, thereby reducing the impact of the first side seal 14 on the width of the secondary battery 100. A second side seal 15 is disposed on the second wall portion 17 and folded toward the second wall portion 17, thereby reducing the impact of the second side seal 15 on the width of the secondary battery 100.

[0079] Along the thickness direction (third direction Z) of the secondary battery 100, the secondary battery 100 has a first main surface 18 and a second main surface 19 that are arranged opposite each other. The first side seal 14 can be folded toward the first main surface 18 or toward the second main surface 19. This can be set as needed to ensure that the first side seal 14 does not exceed the first main surface 18 or the second main surface 19 after folding, thereby reducing the impact of the first side seal 14 on the thickness of the secondary battery 100.

[0080] In other embodiments, the first side seal 14 and the second side seal 15 may also be folded twice, three times, or multiple times. Taking double folding as an example, referring to FIG13 , the first side seal 14 includes a first portion 14a and a second portion 14b. The first portion 14a is connected between the first wall portion 16 and the second portion 14b. The first portion 14a is folded toward the first wall portion 16, and the second portion 14b is folded toward the first portion 14a. After multiple folding, the width of the first side seal 14 can be reduced, thereby reducing the impact of the first side seal 14 on the thickness of the secondary battery 100.

[0081] Before the first fold, the second portion 14b can be folded toward the first portion 14a to reduce the overall width of the first side seal 14. The first portion 14a and the second portion 14b are then folded together toward the first wall 16. After the first portion 14a is folded, along the width direction (second direction Y) of the secondary battery 100, the first portion 14a may be located between the second portion 14b and the first wall 16, or between the first wall 16 and the first portion 14a. In the embodiment of the present application, the second portion 14b is preferably located between the first portion 14a and the first wall 16 to prevent the second portion 14b from warping outside the secondary battery 100.

[0082] Optionally, when the first side seal 14 is folded multiple times, the first part 14a can be located at the outermost side, that is, the outermost layer away from the first wall portion 16. By clamping the first part 14a and the first wall portion 16, the warping of other folded parts can be reduced.

[0083] Regarding the width of each section of the first side seal 14 after folding (along the thickness direction of the secondary battery 100 in the figure, i.e., the third direction Z), the width of the first section 14a can be set to the maximum, ensuring that the first section 14a and the first wall 16 can fully clamp the folded sections between them. Referring to Figure 14 , the first section 14a has a first end 14a1 and a second end 14a2 oppositely disposed. The first end 14a1 is connected to the first wall 16, and the second end 14a2 is connected to the second section 14b. Along the thickness direction of the secondary battery 100 (the third direction Z), the height from the first end 14a1 to the first major surface 18 is H1, the height from the first end 14a1 to the second major surface 19 is H2, and the height from the first end 14a1 to the second end 14a2 is H3; H3 ≤ H1 and / or H3 ≤ H2. After folding, the first section 14a does not extend beyond the first major surface 18 or the second major surface 19, thereby reducing the impact of the first side seal 14 on the thickness of the secondary battery 100.

[0084] Referring to Figure 15 , taking a double fold as an example, after folding, the fourth surface 142 of the second portion 14b faces the fourth surface 142 of the first portion 14a, and the third raised portion 144 on the second portion 14b is at least partially disposed within the fifth recessed area 145 on the first portion 14a. By embedding the third raised portion 144 within the fifth recessed area 145, the thickness of the first side seal 14 after folding can be reduced. This not only reduces the impact of the first side seal 14 on the thickness of the secondary battery 100, but also reduces the impact of the first side seal 14 on the width of the secondary battery 100, thus meeting the requirements for an ultra-thin and miniaturized design of the secondary battery 100. If multiple folding is employed, a similar arrangement can be employed, ensuring that the raised portion can be embedded within the recessed area.

[0085] The second side seal 15 may be configured similarly to the first side seal 14 , and may further enhance the overall packaging strength of the packaging bag 10 .

[0086] Because the first and second side seals 14, 15 employ a zigzag configuration that can be concave or convex, the packaging strength can be increased, further reducing the risk of the first and / or second side seals 14, 15 being ripped open. Furthermore, due to the zigzag configuration, the widths of the first and second side seals 14, 15 are reduced. After folding, the widths of the first and second side seals 14, 15 are relatively small, having little impact on the width of the secondary battery 100. This allows the thickness of the secondary battery 100 to be adaptively reduced, facilitating the ultra-thin and miniaturized design requirements of the secondary battery 100. Optionally, along the thickness direction of the secondary battery 100, the thickness of the secondary battery 100 is T, where T is ≤ 2.6 mm. For example, when the aforementioned single folding method is employed, the thickness T of the secondary battery 100 can be set to 2.3 mm to 2.6 mm, and when the double folding method is employed, the thickness T of the secondary battery 100 can be set to 2 mm to 2.3 mm.

[0087] In a second aspect, the present application further proposes a method for preparing a secondary battery 100, which is used to prepare the secondary battery 100 described in any embodiment of the first aspect. Referring to FIG. 4 and FIG. 7 , the method comprises the following steps:

[0088] A head is provided, comprising a first head 200 and a second head 300, wherein the first head 200 has a convex section 210 and a first straight section 220, and the second head 300 has a concave section 310 and a second straight section 320;

[0089] A packaging bag 10 is provided. The packaging bag 10 has a top seal 13. The tab 30 of the secondary battery 100 extends out of the packaging bag 10 from the top seal 13. The tab 30 can be electrically connected to the electrode assembly 20, and the electrode assembly 20 can be placed in the packaging bag 10. For example, the first bag body 11 and the second bag body 12 described above are used. The tab 30 is placed between the first seal portion 13a of the first bag body 11 and the second seal portion 13b of the second bag body 12. The first seal portion 13a and the second seal portion 13b form the top seal 13.

[0090] The first head 200 and the second head 300 are respectively placed on both sides of the top sealing edge 13 in the thickness direction (third direction Z), wherein the raised section 210 of the first head 200 is opposite to the recessed section 310 of the second head 300, the first straight section 220 of the first head 200 is opposite to the second straight section 320 of the second head 300, and the tab 30 is located between the first straight section 220 and the second straight section 320;

[0091] The first sealing head 200 and the second sealing head 300 are heat-pressed to form the top sealing edge 13 and bonded to form a package. This allows the top sealing edge 13 to have a zigzag arrangement, thereby improving the packaging strength of the secondary battery 100 .

[0092] In a third aspect, an embodiment of the present application further provides an electronic device comprising a secondary battery as described in any embodiment of the first aspect above. The electronic device can be implemented in various specific forms, for example, drones, electric vehicles, electric cleaning tools, energy storage products, electric vehicles, electric bicycles, electric navigation tools and other electronic products. In some scenarios, electrical devices include but are not limited to: backup power supplies, electrodes, automobiles, motorcycles, power-assisted bicycles, bicycle power tools, large household batteries and lithium-ion capacitors, etc.

[0093] Experiment 1: [Drop test of lithium-ion battery]

[0094] Example 1:

[0095] <Preparation of positive electrode sheet>

[0096] The positive electrode active material lithium iron phosphate, the positive electrode conductive agent acetylene black, the positive electrode binder polyvinylidene fluoride (PVDF, weight average molecular weight 5×10 5 ) were mixed in a mass ratio of 94:3:3, and N-methylpyrrolidone (NMP) was added as a solvent. The mixture was stirred in a vacuum mixer until a solid content of 75 wt% and a uniform system was obtained. The positive electrode slurry was evenly coated on one surface of a 6 μm thick positive electrode current collector aluminum foil and dried at 90°C to obtain a positive electrode sheet coated with a positive electrode active material layer (80 μm thick) on one side. The above steps were then repeated on the other surface of the aluminum foil to obtain a positive electrode sheet coated with a positive electrode active material layer on both sides. After cold pressing and slitting, a 10 mm × 35 mm positive electrode tab slot was laser-cut on the positive electrode tab slot. A positive electrode tab with a thickness of 116 μm and a width × length of 5 mm × 55 mm was welded into the positive electrode tab slot to obtain a positive electrode sheet with a specification of 74 mm × 851 mm for future use.

[0097] <Preparation of negative electrode sheet>

[0098] The negative electrode active material graphite powder, conductive carbon black (Super P), and binder styrene-butadiene rubber (SBR) were mixed in a weight ratio of 97.5:1:1.5. Deionized water was then added as a solvent to prepare a slurry with a solid content of 50 wt%, which was then stirred evenly. The slurry was evenly coated on one surface of a 5 μm thick negative electrode current collector copper foil and dried at 110°C to obtain a negative electrode active material weight of 9.1 mg / cm 2Single-sided negative electrode sheet. After completing the above steps, the negative electrode sheet is coated on one side. The above steps are then repeated on the other side of the negative electrode sheet to obtain a negative electrode sheet coated on both sides with a negative electrode active material layer. A 12mm x 35mm negative electrode tab slot is laser-cut on the negative electrode sheet. A 110μm thick negative electrode tab measuring 8mm x 55mm in width and length is welded into the slot. The negative electrode sheet specifications are 76mm x 860mm in width and length.

[0099] <Preparation of Separator>

[0100] A polyethylene (PE) porous film with a thickness of 8 μm was used as the separator.

[0101] <Electrolyte Preparation>

[0102] In a dry argon atmosphere, ethylene carbonate, ethyl methyl carbonate and diethyl carbonate were mixed in a mass ratio of 30:50:20 to obtain an organic solution, and then lithium hexafluorophosphate was added to the organic solvent to dissolve and mix uniformly to obtain an electrolyte with a lithium salt concentration of 1.15 mol / L.

[0103] <Preparation of lithium-ion batteries>

[0104] The prepared separator, positive electrode sheet, separator, and negative electrode sheet were stacked in order and wound to form an electrode assembly. The electrode assembly was then hot-pressed at a pressure of 5 MPa, a temperature of 65°C, and a holding time of 10 seconds. The electrode assembly was placed in an aluminum-plastic film packaging bag, with the positive electrode tab and negative electrode sheet extending from the top seal of the bag. After dehydration at 80°C, the electrolyte was injected and the package was sealed.

[0105] Among them, during packaging, the first head and the second head are used, and the first head and the second head are respectively placed on both sides of the top seal of the packaging bag. The raised section and the recessed section of the first head and the recessed section and the raised section of the second head correspond to the non-ear position of the top seal, so that the top seal forms a concave and convex package. The straight sections of the first head and the second head correspond to the ear positions of the top seal, so that the ear positions form a flat package. The side seals directly use straight heads for flat packaging. The side seals are folded once, and after the formation, degassing, shaping and other process flows, a lithium-ion battery with a thickness of 2.9 mm is obtained, wherein the top seal width (along the length direction of the battery, that is, the direction of the ear extending) is 1 mm, and the top seal length is 50 mm.

[0106] Example 2-6: Different from Example 1, the convex section and the concave section of the first head are smoothly transitioned by an arc chamfer, and the radius R of the arc chamfer is shown in Table 1. The remaining parameters are the same as those of Example 1.

[0107] Example 7: Different from Example 1, both side seals are folded twice.

[0108] Examples 8 and 9: Unlike Example 1, both side seals of the lithium-ion battery are encapsulated in a concave-convex pattern, and the side seals are not flat. The side seals are folded once, resulting in a lithium-ion battery with a thickness of 2.6 mm. The remaining parameters are the same as those of Example 1.

[0109] Comparative Example 1: Both the top and side sealing edges adopt conventional flat packaging.

[0110] Drop test:

[0111] The lithium-ion battery was pre-conditioned at 25°C and allowed to stand at room temperature for 60 minutes. The voltage of the lithium-ion battery was then measured before the drop test. The lithium-ion battery was then placed in a fixture and dropped freely from a height of 1.5m using a drop device in the following order: head-tail-head right corner-tail right corner-head left corner-tail left corner (angle: 45±15°), repeated six times. After the drop, the battery was allowed to stand at room temperature for 24 hours. The voltage of the lithium-ion battery was measured and recorded. The appearance of the lithium-ion battery was inspected and photographed before and after the test. The drop test passing criteria were: no smoke, no leakage, and a voltage drop of <30mV. 100 cells were tested, and the number of cells that passed the test was X, resulting in a test pass rate of X / 100.

[0112] The test results are shown in Table 1 below:

[0113] Table 1

[0114] According to Table 1 above, combined with Comparative Example 1 and Examples 1-7, the top seals of Examples 1-7 all employed a flat package at the tab locations and a concave-convex package at non-tab locations. The battery failure rates in Examples 1-7 were significantly lower than those in Comparative Example 1. The concave-convex zigzag package structure increases the package area, thereby improving the packaging strength of the packaging bag and effectively reducing the risk of the top seal being broken.

[0115] Combining Examples 4 and 8, the side-sealed concave-convex packaging used in Example 8 has a lower drop failure rate, higher packaging strength, and allows for thinner battery configurations. Therefore, in this application, the side-sealed concave-convex packaging configuration is preferred. The same applies to Examples 7 and 9.

[0116] Combining Examples 4 and 7, Example 7 employs a flat package with secondary folding of the side seals, which has a lower risk of failure due to a drop. The secondary folding of the side seals allows the battery thickness to be set thinner. The thinner thickness allows for a more uniform stress distribution when the battery is subjected to internal pressure, reducing the risk of local stress concentration and thus the possibility of the top seal being breached. This not only reduces the risk of battery failure due to a drop, but also reduces the thickness of the battery to an even smaller size, facilitating the ultra-thin design requirements of the battery. Similarly, Examples 8 and 9 employ a concave-convex side seal and secondary folding, which can reduce the battery thickness to 2 mm, further reducing the thickness of the battery and reducing the risk of the top seal being breached.

[0117] Combining Examples 1 to 6, it can be seen that when the concave and convex joints adopt a curved chamfer transition, the risk of battery failure can be further reduced. The curved chamfer can disperse stress and reduce stress concentration, thereby alleviating tearing of the top seal and thus improving the packaging strength of the top seal. In Examples 2-5, the drop failure rate is significantly lower than that of Examples 1 and 6. In this application, the radius of the curved chamfer is preferably 0.4mm≤R≤0.8mm.

[0118] Experiment 2: [Lithium-ion battery top seal strength test]

[0119] Package strength test: Use a high-speed rail tensile testing machine to fix one side of the top seal to the bottom of the machine and the other side to the top of the machine, keeping both sides on the same vertical plane. Set the tensile testing machine speed to 50mm / min, pull the top seal until it opens, and record the tensile force f (in Newtons) at the time of opening. The package strength of the top seal is F (N / mm) = f / W, where W is the package width of the top seal. (When testing the package strength of a straight portion, the tensile testing machine fixes both sides of the straight portion; when testing the package strength of a concave-convex portion, the tensile testing machine fixes both sides of the concave-convex portion, for example, one side fixes the raised portion and the other side fixes the concave portion.)

[0120] The difference between Examples 10-12 and Example 8 is that the width of the top seal edge (along the length direction of the secondary battery, that is, the direction in which the tabs extend) is different. The relevant parameters are shown in Table 2 below:

[0121] Table 2

[0122] According to Table 2 above, combined with Comparative Example 1 and Example 8, with Comparative Example 1 as the basis, when the package strength is similar, when the top seal adopts a concave-convex package + flat package, the width of the top seal is smaller, which is more suitable for miniaturized battery design. Alternatively, at the same width, the top seal of the concave-convex package has higher package strength, which can reduce the risk of the top seal being broken.

[0123] Combining Comparative Example 1, Example 8, and Examples 10-12, when the package width of the top seal exceeds 0.8 mm, the package strength is significantly better than that of Comparative Example 1. Therefore, in this application, the package width W of the top seal is selected to be ≥ 0.8 mm, and the side seals can also be set similarly.

[0124] The above description is merely an embodiment of the present application and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A secondary battery comprising a packaging bag, an electrode assembly, and a tab, wherein the electrode assembly is housed in the packaging bag, the packaging bag having a top seal, one end of the tab being electrically connected to the electrode assembly within the packaging bag, and the other end extending from the top seal outside the packaging bag, characterized in that: The top sealing edge comprises a straight portion and a curved portion connected to each other; The tab extends out of the packaging bag from the straight portion; Along the thickness direction of the secondary battery, the meandering portion has a first surface and a second surface opposite to each other, the first surface has a first concave area concave toward the second surface, and the first concave area forms a first convex portion on the second surface.

2. The secondary battery according to claim 1, wherein The meandering portion includes at least two of the first protrusions; Along the length direction of the secondary battery, the at least two first protrusions are spaced apart from each other, and a second recessed area is formed between two adjacent first protrusions; The second recessed area forms a second protruding portion on the first surface.

3. The secondary battery according to claim 2, wherein The first protrusion is connected to the second recessed area through an arc chamfer.

4. The secondary battery according to claim 3, wherein The radius of the arc chamfer is R, 0.4mm≤R≤0.8mm.

5. The secondary battery according to any one of claims 1 to 4, characterized in that The secondary battery further comprises a first side seal and a second side seal that are arranged opposite to each other; Along the thickness direction of the first side edge seal, the first side edge seal includes a third surface and a fourth surface arranged opposite to each other, the third surface has a third recessed area recessed toward the fourth surface, and the third recessed area forms a third raised portion on the fourth surface; Along the thickness direction of the second side edge seal, the second side edge seal includes a fifth surface and a sixth surface arranged opposite to each other. The fifth surface has a fourth recessed area recessed toward the sixth surface. The fourth recessed area forms a fourth protrusion on the sixth surface.

6. The secondary battery according to claim 5, characterized in that The secondary battery further comprises a first wall portion and a second wall portion which are arranged opposite to each other; The first side seal is provided on the first wall portion, and the first side seal is folded toward the first wall portion; The second side seal is arranged on the second wall portion, and the second side seal is folded toward the second wall portion.

7. The secondary battery according to claim 6, characterized in that The first side seal includes a first portion and a second portion, the first portion is connected between the first wall portion and the second portion, the first portion is folded toward the first wall portion, and the second portion is folded toward the first portion.

8. The secondary battery according to claim 7, wherein The second portion is located between the first portion and the first wall portion in a width direction of the secondary battery.

9. The secondary battery according to claim 8, wherein The first side edge seal includes at least two third protrusions, the at least two third protrusions are spaced apart from each other, a fifth recessed area is formed between two adjacent third protrusions, and the fifth recessed area forms a fifth protrusion on the third surface; The fourth surface of the second part is arranged to face the fourth surface of the first part, and the third protrusion on the second part is at least partially arranged in the fifth recessed area on the first part.

10. The secondary battery according to claim 7, wherein Along the thickness direction of the secondary battery, the secondary battery has a first main surface and a second main surface arranged opposite to each other; the first portion has a first end and a second end arranged opposite to each other, the first end is connected to the first wall portion, and the second end is connected to the second portion; Along the thickness direction of the secondary battery, a height from the first end to the first main surface is H1, a height from the first end to the second main surface is H2, and a height from the first end to the second end is H3; H3≤H1, and / or, H3≤H2.

11. The secondary battery according to any one of claims 1 to 10, characterized in that: Along the thickness direction of the secondary battery, the thickness of the secondary battery is T, and T≤2.6 mm.

12. The secondary battery according to any one of claims 1 to 11, characterized in that: Along the thickness direction of the secondary battery, the top sealing edge includes a first sealing portion and a second sealing portion that are oppositely arranged, the electrode tab is arranged between the first sealing portion and the second sealing portion, and the first sealing portion and the second sealing portion are bonded; In the straight portion, the peel strength between the first sealing portion and the second sealing portion is G1, G1 ≥ 1 N / mm; and / or, In the bending portion, the peel strength between the first sealing portion and the second sealing portion is G2, and G2 is ≥ 1.875 N / mm.

13. The secondary battery according to claim 12, characterized in that The first sealing portion includes a first protective layer, a first sealing layer, and a first metal layer disposed between the first protective layer and the first sealing layer; The second sealing portion includes a second protective layer, a second sealing layer, and a second metal layer disposed between the second protective layer and the second sealing layer; The first sealing layer is bonded to the second sealing layer.

14. The secondary battery according to any one of claims 1 to 13, characterized in that Along the length direction of the secondary battery, the bonding width between the first sealing portion and the second sealing portion is W, and W is greater than or equal to 0.8 mm.

15. A method for preparing a secondary battery according to any one of claims 1 to 14, characterized in that: include: A head is provided, the head comprising a first head and a second head, the first head having a convex section and a first straight section, the second head having a concave section and a second straight section; A packaging bag is provided, wherein the packaging bag has a top seal edge, and the tab of the secondary battery is connected to the top seal edge. extending out of the packaging bag; Place the first head and the second head on both sides of the top seal in the thickness direction, respectively, wherein the convex section of the first head is opposite to the concave section of the second head, the first straight section of the first head is opposite to the second straight section of the second head, and the tab is located between the first straight section and the second straight section; The first sealing head and the second sealing head heat-press the top sealing edge so that the top sealing edge is bonded and sealed.

16. An electronic device, characterized in that: The secondary battery according to any one of claims 1 to 14 is included.

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