Secondary battery and electronic device

Abstract

Disclosed in the present application are a secondary battery and an electronic device. The secondary battery comprises a packaging pouch and an electrode assembly, wherein the packaging pouch comprises a main body portion and a sealing edge portion connected to the main body portion, the main body portion being provided with an accommodating cavity and a first side wall, the accommodating cavity accommodating the electrode assembly. The secondary battery is provided with a recess, wherein the recess is located at the first side wall; the sealing edge portion is provided with a first sealing edge at the recess, the first sealing edge being connected to the first side wall; and the first sealing edge is provided with a protruding portion, the protruding portion being bent and fixed to the first side wall. The protruding portion can disperse stress at the recess of the packaging pouch and prevent distortion and deformation at the recess, so that the strength and tear resistance of said part are improved, thereby improving the dropping resistance and impact resistance of the secondary battery, and also improving the packaging strength of the secondary battery.

Description

Secondary batteries and electronic devices Technical Field

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

[0002] Lithium-ion batteries, as the power source for mobile devices, are key to ensuring their normal use. As mobile devices such as mobile phones and laptops become increasingly popular, their operating conditions are becoming increasingly complex, placing increasing demands on battery safety.

[0003] Batteries will inevitably encounter problems such as falling and bumping during use, especially for polygonal soft-pack batteries, such as "L"-shaped batteries, which have a notch structure. During the falling process, they are subjected to stress from all sides, which can easily cause stress concentration at the notch position, resulting in damage and cracking at the notch position, resulting in battery leakage and failure.

[0004] Summary of the Invention

[0005] The embodiments of the present application aim to provide a secondary battery and an electronic device to reduce battery failure caused by drop and breakage.

[0006] In order to solve the technical problems, the embodiments of the present application adopt the following technical solutions:

[0007] In the first aspect, the present application proposes a secondary battery, including a packaging bag and an electrode assembly, the packaging bag including a main body and a sealing edge portion connected to the main body, the main body having a accommodating cavity and a first side wall, the accommodating cavity accommodating the electrode assembly, the secondary battery having a recess, the recess being located on the first side wall, the sealing edge portion having a first sealing edge at the recess, the first sealing edge being connected to the first side wall, the first sealing edge having a protrusion, and the protrusion being bent and fixed to the first side wall.

[0008] In the above technical solution, the protrusion disperses stress at the notch of the packaging bag and prevents distortion at the notch, thereby increasing the strength and tear resistance of the notch, and thus improving the drop and impact resistance of the secondary battery. Furthermore, the protrusion forms part of the first edge seal and can directly act on the first edge seal. That is, after the protrusion is bent and fixed to the first sidewall, a double-layer protective structure is formed. This not only improves the seal strength of the packaging bag at the notch, reducing the risk of this portion being broken open, but also protects the notch of the packaging bag, increasing the contact area with this portion. This results in a wider and more uniform stress distribution range, further improving the strength and tear resistance of this portion.

[0009] In some preferred embodiments, the secondary battery further comprises a first adhesive layer, the first adhesive layer bonding the protrusion to the first sidewall. The provision of the first adhesive layer can enhance the bonding strength between the protrusion and the first sidewall and improve the tear resistance of the packaging bag at the notch, thereby reducing damage and tearing in this area.

[0010] In some preferred embodiments, when viewed along the thickness direction of the secondary battery, the first side wall is arc-shaped, which can further disperse stress, and the arc shape can increase the contact area with the protrusion, so that the stress is dispersed more widely and evenly, which can further reduce deformation, breakage or tearing at the notch.

[0011] In some preferred embodiments, the protrusion has a top portion fixed to the first side wall, and the first edge seal further includes a connecting portion, through which the protrusion is connected to the main body. Along the thickness direction of the secondary battery, the distance between the top portion and the connecting portion is H μm, with 100 ≤ H ≤ 500. This facilitates bending of the protrusion without affecting the appearance of the secondary battery, allowing for easy attachment and fixation to the first side wall, effectively dispersing stress. Preferably, 250 ≤ H ≤ 300, making the protrusion easier to fold and providing better stress dispersal.

[0012] In some preferred embodiments, the protrusion has a top portion fixed to the first side wall, the first edge seal further includes a connecting portion, the protrusion is connected to the main body portion via the connecting portion, and the protrusion is bent and fixed to the connecting portion.

[0013] In some preferred embodiments, when viewed along the thickness direction of the secondary battery, the radius of the first side wall is R μm, where H≤R, which can reduce the impact of the protrusion on the external dimensions of the secondary battery and facilitate stress dispersion.

[0014] In some preferred embodiments, when viewed along the thickness of the secondary battery, the protrusion further includes a bottom portion connected to the connecting portion. The protrusion further includes a first wall portion connecting the top and bottom portions. When viewed along the thickness of the secondary battery, the first wall portion is arc-shaped, with a radius of R1, where 0.9R1≤R≤1.1R1. The radius of the first wall portion is as consistent as possible with that of the first side wall to facilitate fully and evenly distributing stress.

[0015] In some preferred embodiments, the first edge seal further includes a connecting portion, through which the protrusion is connected to the main body. Observed along the thickness direction of the secondary battery, the connection length between the protrusion and the connecting portion is W μm, with a value of 100 ≤ W ≤ 300. This not only facilitates folding of the protrusion but also effectively disperses stress while improving strength and reducing tearing in the first section. The first direction is the thickness direction of the packaging bag. Preferably, 200 ≤ W ≤ 250 makes folding of the protrusion easier and provides better stress dispersion.

[0016] In some preferred embodiments, the edge sealing portion further includes a top edge sealing portion, the secondary battery includes a tab and tab glue, the tab glue is at least partially disposed on the top edge sealing portion, and the tab is connected to the top edge sealing portion through the tab glue. The melting point of the tab glue is T°C, 100≤T≤130. When thermal runaway occurs in the secondary battery, its temperature will quickly reach the above-mentioned predetermined threshold (100°C to 130°C), at which time the tab glue melts and forms a pressure relief channel between the tab and the top edge sealing portion, which can quickly discharge heat and gas in the packaging bag, thereby reducing the risk of explosion of the secondary battery.

[0017] In some preferred embodiments, the secondary battery includes an electrolyte, which is contained in the housing. The electrolyte includes at least one of ethylene carbonate, vinylene carbonate, polypropylene sulfonate, sulfite, fluoroethylene carbonate, or a halogenated carbonate. The electrolyte system is optimized to reduce heat generation in the secondary battery.

[0018] In a second aspect, the present application further proposes an electronic device comprising a secondary battery as described in any embodiment of the first aspect above.

[0019] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] One or more embodiments are exemplarily illustrated 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 figures in the drawings do not constitute proportional limitations.

[0021] FIG1 is an exploded view of a secondary battery according to some embodiments of the present application;

[0022] FIG2 is a schematic diagram of the structure of stacked layers of the first shell or the second shell in some embodiments of the present application;

[0023] FIG3 is a schematic structural diagram of a secondary battery according to some embodiments of the present application (the protrusion is not bent);

[0024] FIG4 is a schematic structural diagram of a secondary battery in some embodiments of the present application (with a convex portion bent);

[0025] FIG5 is a schematic structural diagram of a secondary battery according to some embodiments of the present application (provided with a first adhesive layer);

[0026] FIG6 is a schematic structural diagram of a notch in some embodiments of the present application;

[0027] FIG7 is a schematic diagram of fixing a protrusion to a first side wall in some embodiments of the present application;

[0028] FIG8 is a schematic structural diagram of a notch in some embodiments of the present application;

[0029] FIG9 is a schematic structural diagram of various protrusions in some embodiments of the present application;

[0030] FIG10 is a schematic structural diagram of a notch in some embodiments of the present application.

[0031] Explanation of the accompanying drawings: 100, secondary battery; 10, packaging bag; 11, first shell; 111, first cavity; 12, second shell; 101, metal layer; 102, protective layer; 103, sealing layer; 10a, main body; 10a1, first side wall; 10b, edge sealing portion; 10b1, top edge sealing; 10b2, first edge sealing; 10b21, protrusion; b211, top; b212, bottom; b213, first wall; b214, second wall; 10b22, connecting portion; 10c, notch; 20, electrode assembly; 30, tab; 40, first glue layer; 50, tab glue; Z, first direction; Y, second direction; X, third direction; N, fourth direction; M, fifth direction. DETAILED DESCRIPTION

[0032] The following embodiments of the technical solution of the present application will be described in detail with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application and are therefore only examples and are not intended to limit the scope of protection of the present application.

[0033] It should be noted that when an element is described as being “fixed to” or “disposed on” another element, it may be directly on the other element, or one or more intervening elements may be present therebetween. When an element is described as being “connected to” another element, it may be directly connected to the other element, or one or more intervening elements may be present therebetween.

[0034] In the description of the embodiments of this application, the technical terms "first," "second," etc. are used only to distinguish different objects and should not be understood to indicate or imply relative importance or to implicitly indicate 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 specifically defined.

[0035] 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.

[0036] References to "embodiments" herein mean that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the present 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 with other embodiments. Furthermore, the technical features described below in the different embodiments of the present application may be combined with each other as long as they do not conflict with each other.

[0037] Secondary batteries, as the power source for mobile devices, are key to ensuring their normal use. As mobile devices such as mobile phones and laptops become increasingly popular, their operating conditions are becoming increasingly complex, placing increasing demands on battery safety.

[0038] The inventors of the present application discovered in the process of implementing the present application that secondary batteries are inevitably subject to problems such as falling and bumping during use, especially for polygonal (e.g., L-shaped) secondary batteries, which usually include a notch structure at the corners. During the falling process, the secondary battery will be subjected to stress and pulling from all aspects, and it is easy to cause stress concentration at the notch position of the secondary battery, resulting in damage and cracking at the notch position, so that the secondary battery leaks and fails.

[0039] To address this issue, a commonly used technique currently relies on adding an adhesive layer to the notch of the secondary battery to mitigate the impact force. The adhesive layer can increase the tensile strength of the secondary battery surface, thereby reducing stress concentration at the notch. However, this method only enhances the tensile strength of the surface at the notch. The secondary battery casing (packaging bag) typically includes a multi-layer structure, such as a sealing layer, a protective layer, and a metal layer located between the sealing and protective layers. If the stress at this location directly pulls on the metal layer, the external adhesive layer will not provide sufficient protection, and the risk of damage and leakage will still exist.

[0040] In order to alleviate the above-mentioned problems, on the first hand, the present application proposes a secondary battery 100. Please refer to FIG1 . The secondary battery 100 includes a packaging bag 10, an electrode assembly 20 and a tab 30. The packaging bag 10 is the mounting base and container for the other components of the secondary battery 100. The electrode assembly 20 is contained in the packaging bag 10. The electrode assembly 20 is the core component for the secondary battery 100 to realize charging and discharging. One end of the tab 30 is electrically connected to the electrode assembly 20, and the other end extends out of the packaging bag 10. Next, taking the secondary battery 100 as a lithium-ion battery as an example, the specific structure of the secondary battery 100 is explained; it can be understood that in other embodiments of the present application, the secondary battery 100 can also be a secondary battery 100 in other forms such as a sodium-ion battery.

[0041] Regarding the packaging bag 10, please refer to FIG1 . The packaging bag 10 can be made of a flexible material, which constitutes the mounting base, container, and outer protective structure of the secondary battery 100. The packaging bag 10 defines a housing cavity (not shown in the figure), which can be used to accommodate the electrolyte (not shown in the figure) and the electrode assembly 20. For example, the packaging bag 10 includes a first shell 11 and a second shell 12. Please further refer to FIG2 . The first shell 11 and the second shell 12 both include a sealing layer 103, a metal layer 101, and a protective layer 102 stacked in sequence. The first shell 11 is provided with a first cavity 111, and the second shell 12 is provided with a second cavity (not shown in the figure). The electrode assembly 20 can be placed in the first cavity 111. The second shell 12 covers the first cavity 111 of the first shell 11, and the second cavity communicates with the first cavity 111 to form a housing cavity. By hot-pressing the connection between the edges of the two shells, the sealing layers 103 of the two shells can be bonded to each other to seal the housing cavity. Among them, before hot pressing packaging, the first shell 11 and the second shell 12 can be interconnected structures or separated structures. The above-mentioned second shell 12 may not be provided with a pit cavity. The second shell 12 directly covers the first pit cavity 111 of the first shell 11, and the first pit cavity 111 forms a accommodating cavity.

[0042] Alternatively, the packaging bag 10 may have a polygonal structure. For example, referring to Figures 1 and 3 , the packaging bag 10, viewed along the first direction Z, is generally L-shaped. For example, the first shell 11 and the second shell 12 are both L-shaped, and the first shell 11 and the second shell 12 can be combined and connected to form a complete L-shaped packaging bag 10. The bent corners of the L-shaped packaging bag 10 form notches 10c. By configuring the secondary battery 100 in an L-shape, the bag can accommodate the specific battery installation space of an electronic device, significantly increasing the energy density of the secondary battery 100 while reducing the occupied space.

[0043] It can be understood that in the embodiments of the present application, the packaging bag 10 includes but is not limited to an "L"-shaped structure. In other embodiments, the packaging bag 10 may also adopt a polygonal structure with a notch 10c, such as a "Z"-shaped, trapezoidal or rectangular structure, and the number of notches 10c may be two, three or more.

[0044] The packaging bag 10 includes a main body 10a and a sealing edge 10b connected to the main body 10a. The main body 10a encloses the aforementioned accommodating cavity to accommodate the aforementioned electrode assembly 20. The sealing edge 10b is formed at the junction of the two shell edges during hot pressing, i.e., on the exterior of the main body 10a. The sealing edge 10b includes a top sealing edge 10b1. The tab 30 can extend from the top sealing edge 10b1 along a third direction X outside the packaging bag 10 (typically, the portion of the secondary battery 100 where the tab 30 is provided is referred to as the top b211 of the secondary battery 100, and the sealing edge of the top b211 is referred to as the top sealing edge 10b1).

[0045] 3 , the main body 10a has a first sidewall 10a1 , and the notch 10c of the secondary battery 100 is located on the first sidewall 10a1 . The edge sealing portion 10b has a first edge sealing 10b2 at the notch 10c , and the first edge sealing 10b2 is connected to the first sidewall 10a1 .

[0046] The notch 10c is located at the bending corner of the secondary battery 100. For example, the secondary battery 100 includes a first part (not shown in the figure) and a second part (not shown in the figure). The first part and the second part are arranged in sequence in the second direction Y, and the first part and the second part are bent along the notch. The portion of the packaging bag 10 located at the notch 10c is relatively weak. When the secondary battery 100 or an electronic device equipped with the secondary battery 100 accidentally falls or collides, it is easy to cause the packaging bag 10 to bend and deform at the notch 10c. The portion of the packaging bag 10 located at the notch 10c is relatively weak, and stress concentration will occur in this portion, resulting in tearing and damage, which in turn leads to the disadvantage of electrolyte leakage or impurities such as moisture and dust entering the packaging bag 10, thereby causing the secondary battery 100 to fail. To reduce this risk, in an embodiment of the present application, the first edge seal 10b2 also includes a protrusion 10b21. The protrusion 10b21 can disperse the stress of the portion of the packaging bag 10 located at the recess 10c, and can prevent the distortion of the portion, thereby improving the strength and tear resistance of the portion, and thereby improving the anti-collision performance of the secondary battery 100.

[0047] Please further refer to Figure 4. The protrusion 10b21 is bent and fixed to the first side wall 10a1. The protrusion 10b21 is a part of the first edge seal 10b2 and can directly act on the protective layer 102, the metal layer 101 and the sealing layer 103 of the first edge seal 10b2. That is, after the protrusion 10b21 is bent and fixed to the first wall portion b213, a protective structure of a double-layer protective layer 102, a double-layer metal layer 101 and a double-layer sealing layer 103 can be formed at the recess 10c. This not only improves the sealing strength of the packaging bag 10 located at the recess 10c and reduces the risk of this part being opened, but also protects the part of the packaging bag 10 located at the recess 10c, increases the contact area with this part, and makes the stress dispersion range larger and more uniform, thereby further improving the strength and tear resistance of this part.

[0048] In some embodiments, referring to FIG. 5 , the secondary battery 100 further includes a first adhesive layer 40, which bonds the protrusion 10b21 to the first sidewall 10a1. For example, after the protrusion 10b21 is bent and fixed to the first sidewall 10a1, a glue droplet is applied to the protrusion 10b21. The adhesive is cast onto the first sidewall 10a1 and bonded to the first sidewall 10a1. Once the adhesive is dried and fixed, the first adhesive layer 40 is formed. This can further stabilize the attachment of the protrusion 10b21 to the first sidewall 10a1 and reduce deformation of the protrusion 10b21. Alternatively, before bending the protrusion 10b21, the adhesive droplet is applied directly to the first sidewall 10a1. While the adhesive is still wet, the protrusion 10b21 is bent toward the adhesive, allowing the adhesive to bond the protrusion 10b21 to the first sidewall 10a1. The adhesive may be AB glue or epoxy resin glue, etc. The first adhesive layer 40 can improve the bonding strength between the protrusion 10b21 and the first side wall 10a1 and improve the tear resistance of the packaging bag 10 at the notch 10c, thereby reducing the damage and tearing of this part.

[0049] The protrusion 10b21 is a part of the first edge seal 10b2, that is, the protrusion 10b21 and the packaging bag 10 are integrally arranged. The protrusion 10b21 can be protruded in advance on the first shell 11 and / or the second shell 12. After the two shells are connected, the protrusion 10b21 of the first shell 11 and the protrusion 10b21 of the second shell 12 are directly fitted and connected to improve the bonding strength of the protrusions 10b21 of the two shells.

[0050] Optionally, referring to FIG6 , when viewed along the thickness direction of the secondary battery 100 (first direction Z), the first side wall 10a1 is arc-shaped, which causes the recess 10c to appear as an arc-shaped recess 10c. The arc-shaped structure can reduce stress concentration and disperse stress more evenly. The structure, similar to an arched bridge, can reduce damage and tearing at the recess 10c. The protrusion 10b21 is fixed to the arc-shaped first side wall 10a1, which can further disperse stress. The arc shape can also increase the contact area with the protrusion 10b21, resulting in a wider and more even stress dispersion, which can further reduce deformation, damage, or tearing of the protrusion 10b21 or the first side wall 10a1.

[0051] Regarding the height of the protrusion 10b21, if it is too large, it will not only affect the appearance of the secondary battery 100, but may also affect the installation of the secondary battery 100 on the electronic device. Moreover, if the height is too large, it will not be conducive to the protrusion 10b21 and the first side wall 10a1. If the height is too small, it may lead to insufficient strength and insufficient stress dispersion, and it will be difficult to fold. In the embodiment of the present application, please refer to Figures 6 and 7. The protrusion 10b21 has a top b211 fixed to the first side wall 10a1. The first edge seal 10b2 also includes a connecting portion 10b22, and the protrusion 10b21 is connected to the main body 10a via the connecting portion 10b22. Along the thickness direction (first direction Z) of the secondary battery 100, the distance between the top portion b211 and the connecting portion 10b22 is H μm, with 100 ≤ H ≤ 500. This facilitates the bending of the protrusion 10b21 without affecting the appearance of the secondary battery 100, so that it can be fixed to the first side wall 10a1 and fully disperse stress. Preferably, 250 ≤ H ≤ 300, so that the protrusion 10b21 is easier to fold and has a better stress dispersion effect. At the same time, the protrusion 10b21 does not protrude in the thickness direction of the secondary battery 100, and does not affect the appearance of the secondary battery 100. In some embodiments, the protrusion 10b21 is bent and fixed to the connecting portion 10b22, which can enhance the strength of the connecting portion 10b22 and reduce the risk of tearing.

[0052] Regarding the connection length between the protrusion 10b21 and the connection portion 10b22, if the connection length is too long, it will not only be difficult to fold, but also difficult to bend and fix with the first side wall 10a1, and it may also interfere with the installation of the secondary battery 100 on the electronic device. If the connection length is too short, the stress dispersion is poor, the connection strength is insufficient, and it may break after bending. In the embodiment of the present application, please refer to Figure 6, and observe along the thickness direction of the secondary battery 100 (first direction Z), the connection length between the protrusion 10b21 and the connection portion 10b22 is Wμm, 100≤W≤300, which not only facilitates the folding of the protrusion 10b21, but also fully disperses the stress while improving the strength, reducing the tearing of the first section. Preferably, 200≤W≤250, the protrusion 10b21 is easier to fold, and the stress dispersion effect is better. It can be understood that when the connection between the protrusion 10b21 and the connecting portion 10b22 is a straight line, W is the length of the straight line; when the connection between the protrusion 10b21 and the connecting portion 10b22 is an arc surface, the part where the protrusion 10b21 is connected to the packaging bag 10 is also arc-shaped, and the connection length here is the length of the connecting arc.

[0053] Referring to Figure 8 , for the radius R of the arc-shaped first sidewall 10a1, the height distance from the top b211 of the protrusion 10b21 to the connecting portion 10b22 can be set with reference to the radius R of the first sidewall 10a1. Typically, the height H of the protrusion 10b21 needs to be set to be less than or equal to the radius of the first sidewall 10a1, i.e., H ≤ R. This can reduce the impact of the protrusion 10b21 on the external dimensions of the secondary battery 100 and facilitate stress dispersion. The radius of the first sidewall 10a1 can be its own radius or the radius of the fitting circle P within which the first sidewall 10a1 lies. For heavier secondary batteries 100, the stress distribution at the recess 10c can be improved by increasing the radius R. As R increases, the height and area of ​​the corresponding protrusion 10b21 will increase, thereby fully dispersing the stress.

[0054] With reference to Figures 8 and 9 , the protrusion 10b21, viewed along the first direction Z, includes a bottom portion b212 connected to the first edge seal 10b2, a top portion b211 fixed to the first side wall 10a1, and a first wall portion b213 and a second wall portion b214 connecting the top portion b211 and the bottom portion b212. When viewed along the first direction Z, the top portion b211 and the bottom portion b212 are disposed opposite each other along a fourth direction N, and the first wall portion b213 and the second wall portion b214 are disposed opposite each other along a fifth direction M. The top portion b211 can be configured to mate with the first side wall 10a1 to facilitate bending and fixing to the first side wall 10a1. The top portion b211 may be arc-shaped, convexly convexly facing away from the bottom portion b212, to further disperse stress and enhance the strength of the protrusion 10b21. Alternatively, the top portion b211 may be arc-shaped, concavely concavely convexly toward the bottom portion b212, substantially reducing the space occupied by the protrusion 10b21. Alternatively, the top portion b211 may be flat, and optionally, the width of the top portion b211 may be smaller than the width of the bottom portion b212, thereby reducing the space occupied by the protrusion 10b21 while ensuring the connection strength between the protrusion 10b21 and the connecting portion 10b22. When viewed along the first direction Z, the shape of the protrusion 10b21 may be trapezoidal, rectangular, triangular, polygonal, or the like.

[0055] Referring further to FIG. 10 , to further enhance the stress dispersing capability of the protrusion 10b21, the first wall b213 may be configured in an arc shape, for example, concave toward the second wall b214. The second wall b214 connects the top b211 and the bottom b212, thereby reducing the space occupied by the protrusion 10b21 and enhancing the stress dispersing capability of the protrusion 10b21. The radius of the first wall b213 is R1, where 0.9R1≤R≤1.1R1. For example, if the radius R of the first sidewall 10a1 is 100μm to 500μm, the radius R1 of the first wall b213 may be selected to be 90μm to 550μm, ensuring that the radius of the first wall b213 is as consistent as possible with that of the first sidewall 10a1 to facilitate fully and evenly dispersing stress. The radius of the first wall portion b213 may be the radius of the first wall portion b213 itself, or the radius of the fitting circle Q where the first wall portion b213 is located.

[0056] In some other embodiments, the first wall portion b213 may also be in an arc shape that bulges away from the second wall portion b214. Optionally, the second wall portion b214 may also be in an arc shape similar to the first wall portion b213 to fully enhance the strength and stress dispersion effect of the protrusion 10b21.

[0057] When the secondary battery 100 is in a high temperature environment or in the process of long-term charge and discharge cycles, the heat generated by the secondary battery 100 will accumulate in the packaging bag 10. When the accumulation reaches a certain level, thermal runaway of the battery may occur, such as battery expansion or even explosion. To alleviate this problem, in an embodiment of the present application, the secondary battery 100 also includes a tab glue 50 (dashed line portion in Figure 3). The tab glue 50 is at least partially disposed on the top seal 10b1, and the tab 30 is connected to the top seal 10b1 through the tab glue 50. The tab glue 50 can fill the gap between the tab 30 and the top seal 10b1 to ensure the sealing of the packaging bag 10. The tab glue 50 is configured to melt when the temperature rises to a predetermined threshold. For example, the melting point of the tab glue 50 is T°C, 100≤T≤130°C. When the secondary battery 100 experiences thermal runaway, its temperature quickly reaches the predetermined threshold (100°C to 130°C). At this time, the tab glue 50 melts and forms a pressure relief channel between the tab 30 and the top seal 10b1, which can quickly discharge heat and gas within the packaging bag 10, thereby reducing the risk of explosion of the secondary battery 100. The material of the tab glue 50 can be selected from polypropylene, low-density polyethylene, high-density polyethylene, linear low-density polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyethylene terephthalate, polyamide, or phenolic resin.

[0058] In some other embodiments, heat generation can also be reduced by optimizing the electrolyte system, for example, the electrolyte includes lithium salt compounds, carbonate solvents and additives. Lithium salt compounds include lithium hexafluorophosphate, lithium tetrafluoroborate or lithium perchlorate, etc., which are used to provide lithium ion transfer. Carbonate solvents include propylene glycol dimethyl ether, dimethyl dimethyl carbonate, ethylene dimethyl carbonate, etc., which are used as solvents for lithium salts and carriers of electrolytes. Additives include flame retardants and inhibitors. Among them, at least one of ethylene carbonate, vinylene carbonate, polypropylene sulfonate, sulfite, fluoroethylene carbonate or halogenated carbonate can also be added to the electrolyte to optimize the electrolyte system and reduce heat generation of the secondary battery 100.

[0059] In the embodiment of the present application, the protrusion 10b21 can disperse stress at the notch 10c of the packaging bag 10 and prevent distortion at the notch 10c, thereby improving the strength and tear resistance of the notch 10c and further enhancing the drop and impact resistance of the secondary battery 100. Furthermore, the protrusion 10b21 is part of the first edge seal 10b2 and can directly act on the first edge seal 10b2. Specifically, after the protrusion 10b21 is bent and fixed to the first sidewall 10a1, a double-layer protective structure is formed. This not only improves the seal strength of the packaging bag 10 at the notch 10c and reduces the risk of this portion being broken open, but also protects the notch 10c of the packaging bag 10, increasing the contact area with this portion. This allows for a wider and more uniform stress distribution range, further enhancing the strength and tear resistance of this portion.

[0060] In a second aspect, the present application further provides an electronic device comprising the secondary battery 100 described in any embodiment of the first aspect. The electronic device of the embodiments of the present application is not particularly limited and can be any electronic device known in the prior art. For example, electronic devices include, but are not limited to, Bluetooth headsets, mobile phones, tablets, laptops, electric toys, power tools, battery-powered vehicles, electric vehicles, ships, spacecraft, and the like. Among them, electric toys can include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, and spacecraft can include airplanes, rockets, space shuttles, and spacecraft, and the like.

[0061] In the embodiment of the present application, a lithium-ion battery is taken as an example and a drop test is performed on it.

[0062] Example 1

[0063] Preparation of lithium-ion batteries

[0064] (1) Preparation of positive electrode sheet: The positive electrode active material lithium cobalt oxide (LiCoO2), conductive carbon black (Super P), and polyvinylidene fluoride (PVDF) are mixed in a weight ratio of 97.5:1.0:1.5, and N-methylpyrrolidone (NMP) is added as a solvent to prepare a slurry with a solid content of 75wt%, and stirred evenly. The slurry is evenly coated on one surface of a positive electrode current collector aluminum foil with a thickness of 12μm, and dried to obtain a positive electrode sheet coated with a positive electrode active layer on one side. The above steps are repeated on the other surface of the positive electrode current collector aluminum foil to obtain a positive electrode sheet coated with a positive electrode active layer on both sides. It is cold pressed and cut into L-shape for use.

[0065] (2) Preparation of negative electrode sheet: Using graphite as the negative electrode active material, the negative electrode active material graphite, the binder styrene butadiene rubber (SBR) and the thickener sodium carboxymethyl cellulose (CMC) are mixed in a weight ratio of 96:2:2, deionized water is added as a solvent, and a slurry with a solid content of 70wt% is prepared and stirred evenly. Copper foil is selected as the negative electrode current collector, and the slurry is evenly coated on one surface of a negative electrode current collector copper foil with a thickness of 10μm, and dried to obtain a negative electrode sheet coated with a negative electrode active layer on one side. Repeat the above steps on the other surface of the negative electrode current collector copper foil to obtain a negative electrode sheet coated with a negative electrode active layer on both sides. After cold pressing, the negative electrode sheet is cut into an L shape for standby use.

[0066] (3) Preparation of electrolyte: In a dry argon atmosphere, ethylene carbonate (EC), ethyl methyl carbonate (EMC) and diethyl carbonate (DEC) were first mixed in a mass ratio of EC:EMC:DEC = 30:50:20 to form a basic organic solvent. Then, lithium salt lithium hexafluorophosphate (LiPF6) was added to the basic organic solvent to dissolve and mix evenly to obtain an electrolyte with a LiPF6 mass concentration of 12.5%.

[0067] (4) Preparation of isolation membrane: A polyethylene porous membrane is used as a substrate layer, and a ceramic layer containing alumina ceramic and PVDF binder is coated on one surface of the substrate layer as a separator (CCS), wherein the mass percentage of alumina ceramic in the ceramic layer is 95%.

[0068] (5) Electrode assembly preparation: Aluminum sheets are used as positive electrode tabs and welded to the aluminum foil of the positive electrode sheet. Nickel sheets are used as negative electrode tabs and welded directly to the copper foil of the negative electrode sheet. The positive electrode sheets, separators, and negative electrode sheets are alternately stacked in sequence, with separators placed between adjacent positive and negative electrode sheets to form an electrode assembly for future use.

[0069] (6) Electrode assembly assembly: Place the aluminum-plastic film with the pits formed in the assembly fixture with the pits facing upwards, place the electrode assembly in the pits, and set low-density polyethylene ear glue at the two ears, and apply external force to press them tightly. Then, another punched aluminum-plastic film is placed face down to cover the electrode assembly, and the two aluminum-plastic films are heat-sealed on all sides by hot pressing to obtain an L-shaped aluminum-plastic film packaging bag with a sealed edge. The ear glue is between the ear and the top sealed edge, and the first side wall of the packaging bag is enclosed to form an arc-shaped recess structure. The radius of the arc-shaped recess (first side wall) R is 300μm, and a part is reserved in the recess to form a protrusion. An arc-shaped structure (first wall and / or second wall) with a radius R1 of 300μm is cut out on both sides of the protrusion, wherein the connection length W between the protrusion and the edge seal (the connecting part of the edge seal) is 50μm, and the protrusion is ejected by a pin mechanism to be fixed to the first side wall of the packaging bag, and the distance H from the protrusion to the edge seal (the connecting part of the edge seal) is 250μm.

[0070] (7) Liquid injection packaging: The assembled electrode assembly is injected with electrolyte, and after vacuum packaging, static standing, hot pressing, shaping and other processes, the lithium-ion battery is produced.

[0071] Various parameters of Examples 2 to 30 and Comparative Example 1 are shown in Table 1 below.

[0072] Drop test:

[0073] The lithium-ion battery was pre-treated at 25°C, left at room temperature for 60 minutes, and fully cycled for 5 times before adjusting the voltage to 50% SOC. The lithium-ion battery was placed in a fixture and dropped freely from a height of 1.5m above the ground using a drop device in the following order: head-tail-right corner of the head-right corner of the tail-left corner of the head-left corner of the tail (angle: 45±15°). 100 batteries were tested. After the drop test, the appearance of the lithium-ion battery was inspected. The pass criteria for the drop test were: no smoke, no fire, no leakage, and no tearing at the notch. The test results are shown in Table 1 below.

[0074] Table 1

[0075] According to Table 1, combined with Examples 1 to 7 and Comparative Example 1, the placement of a protrusion at the location of the notch effectively reduces drop failure of lithium-ion batteries. This is because the protrusion disperses stress in the portion of the packaging bag located at the notch, preventing distortion and deformation in that portion, thereby improving the strength and tear resistance of that portion. Furthermore, the protrusion, as part of the first side seal, directly acts on the first side seal. This not only enhances the seal strength of the packaging bag located at the notch, reducing the risk of this portion being broken open, but also increases the contact area with that portion, resulting in a wider and more uniform stress distribution, further enhancing the strength and tear resistance of that portion.

[0076] In Examples 2 to 6, the drop failure rate is better than that of Example 1. In Example 2, the connection length is smaller and the space occupied is smaller, and its drop failure rate is consistent with that of Example 7. Therefore, in order to improve the energy density of the secondary battery and reduce the interference of the protrusion on the secondary battery, in this application, 100≤W≤300 can be selected. In combination with Examples 4 and 5, preferably, 200≤W≤250, the lithium-ion battery has better impact resistance and drop resistance. In combination with Example 4 and Example 8, when the first side wall of the packaging bag is arc-shaped, the collision resistance of the lithium-ion battery can be effectively improved. This is because the arc-shaped stress is more evenly dispersed, reducing stress concentration and thus reducing tearing.

[0077] In Examples 10 and 16, the drop failure is significantly better than that in Example 9 and Example 17. The height of the protrusion does not exceed 500 μm, so that the protrusion does not affect the thickness of the secondary battery. When the battery falls, the protrusion pulls less on the edge sealing portion, which can reduce the tearing of the packaging bag. In addition, the height of the protrusion does not exceed 100 μm, ensuring uniform stress distribution and reducing stress concentration. At the same time, it can also facilitate the bending of the protrusion, so that the protrusion is bent and fixed to the first side wall to fully disperse the stress. Therefore, in this application, 100≤H≤500 is selected. In combination with Example 4 and Example 13, preferably, 250≤H≤300.

[0078] In addition, in Examples 14 to 17, the protrusion height H is greater than or equal to the radius R of the first sidewall. A smaller first sidewall radius R makes it difficult to disperse stress over an overly large protrusion, resulting in a smaller stress dispersion range and possible stress concentration, which significantly degrades the drop resistance. Comparing Examples 14 and 18, Examples 15 and 19, Examples 16 and 20, and Examples 17 and 21, it can be seen that when H ≤ R, the drop failure risk of the lithium-ion battery can be effectively reduced. Therefore, in this application, H ≤ R can be selected.

[0079] In Examples 24 to 29, the risk of drop failure is better than that of Examples 22, 23, and 30. In Examples 24 to 29, the first sidewall radius R is similar to the first wall radius R1, which can reduce stress concentration and more evenly distribute stress, thereby reducing the drop risk of the lithium-ion battery. Therefore, in this application, 0.9R1≤R≤1.1R1 can be selected to ensure that the radius of the first sidewall and the first wall is consistent as much as possible, thereby fully and evenly distributing stress.

[0080] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Based on the concept of the present application, the technical features in the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations in different aspects of the present application as described above. For the sake of simplicity, they are not provided in detail. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A secondary battery, comprising a packaging bag and an electrode assembly. The packaging bag includes a main body portion and a sealing edge portion connected to the main body portion. The main body portion has a receiving cavity and a first side wall. The receiving cavity houses the electrode assembly. It is characterized in that: The secondary battery has a notch located on the first side wall. The sealing edge portion has a first sealing edge at the notch. The first sealing edge is connected to the first side wall. The first sealing edge has a protruding portion, and the protruding portion is bent and fixed to the first side wall.

2. The secondary battery according to claim 1, characterized in that, The secondary battery further includes a first adhesive layer that bonds the protruding portion and the first side wall.

3. The secondary battery according to claim 1, wherein When observed in the thickness direction of the secondary battery, the first side wall is arc-shaped.

4. The secondary battery according to claim 3, characterized in that, The protruding portion has a top fixed to the first side wall. The first sealing edge further includes a connecting portion. The protruding portion is connected to the main body portion through the connecting portion. In the thickness direction of the secondary battery, the distance between the top and the connecting portion is H μm, where 100 ≤ H ≤ 500.

5. The secondary battery according to claim 4, characterized in that, 250≤H≤300。 6. The secondary battery according to claim 4, characterized in that, When observed in the thickness direction of the secondary battery, the radius of the first side wall is R μm, and H ≤ R.

7. The secondary battery according to claim 6, characterized in that, When observed in the thickness direction of the secondary battery, the protruding portion further has a bottom connected to the connecting portion. The protruding portion further has a first wall portion connecting the top and the bottom. When observed in the thickness direction of the secondary battery, the first wall portion is arc-shaped, and the radius of the first wall portion is R1, where 0.9R1 ≤ R ≤ 1.1R1.

8. The secondary battery according to claim 1, wherein The first sealing edge further includes a connecting portion. The protruding portion is connected to the main body portion through the connecting portion. When observed in the thickness direction of the secondary battery, the connection length between the protruding portion and the connecting portion is W μm, where 100 ≤ W ≤ 300.

9. The secondary battery according to claim 8, characterized in that, 200≤W≤250。 10. The secondary battery according to claim 1, characterized in that, The sealing edge portion further includes a top sealing edge. The secondary battery includes a tab and a tab adhesive. The tab adhesive is at least partially disposed on the top sealing edge, and the tab is connected to the top sealing edge through the tab adhesive. The melting point of the tab adhesive is T °C, where 100 ≤ T ≤ 130.

11. The secondary battery according to claim 1, characterized in that, The secondary battery includes an electrolyte, and the electrolyte is received in the receiving cavity. The electrolyte includes at least one of ethylene carbonate, vinylene carbonate, polypropylene sulfonate, sulfite, fluoroethylene carbonate, or halogenated carbonate.

12. The secondary battery according to claim 1, characterized in that, The protruding portion has a top fixed to the first side wall. The first sealing edge further includes a connecting portion. The protruding portion is connected to the main body portion through the connecting portion, and the protruding portion is bent and fixed to the connecting portion.

13. An electronic device, characterized in that, Including the secondary battery according to any one of claims 1 to 12.

Images