Secondary battery, electronic device, and method for manufacturing secondary battery

Abstract

The invention relates to a secondary battery, electronic equipment and a manufacturing method of the secondary battery, the secondary battery comprises a shell and an electrode assembly, the shell comprises a packaging film, and the packaging film wraps the outer surface of the electrode assembly. The shell further comprises an adhesive layer, the adhesive layer is arranged on the surface, away from the electrode assembly, of the packaging film, the adhesive layer comprises a lipid compound, the tensile elongation at break of the packaging film is phi 1, and the tensile elongation at break of the part, provided with the adhesive layer, of the shell is phi 2 and phi 2lt; phi 1. According to the secondary battery, the electronic equipment and the manufacturing method of the secondary battery, the problem of short circuit of the secondary battery can be solved.

Description

Technical Field

[0001] The present application relates to the technical field of batteries, and particularly to a secondary battery, an electronic device, and a manufacturing method of the secondary battery. Background Art

[0002] As the power source of an electronic device, a secondary battery is the key to ensuring the normal use of the electronic device. When the secondary battery is damaged by an external force, it is likely to cause an internal short circuit, thus bringing safety problems such as thermal runaway. Summary of the Invention

[0003] The inventors of the present application have found through research that when the secondary battery is damaged by an external force, the packaging film is easily extended to the electrode plate by the external force, resulting in the contact between the aluminum layer of the packaging film and the electrode plate, thus causing a short circuit. By coating an adhesive layer with a tensile fracture elongation lower than that of the packaging film on the outer surface of the packaging film of the finished secondary battery, so that the housing has the adhesive layer and the packaging film, the tensile fracture elongation of the part of the housing provided with the adhesive layer can be lower than that of the original packaging film. When the secondary battery is damaged by an external force, the housing can break in advance, and the extension of the aluminum layer in the packaging film is reduced when breaking, thereby reducing the possibility of the aluminum layer being extended greatly and contacting the electrode plate to cause a short circuit.

[0004] The purpose of the present application is to provide a secondary battery, an electronic device, and a manufacturing method of the secondary battery, aiming to improve the problem of short circuit of the secondary battery.

[0005] According to the first aspect of the present application, there is provided a secondary battery, including a housing and an electrode assembly. The housing includes a packaging film, and the packaging film wraps around the outer surface of the electrode assembly. The housing further includes an adhesive layer, and the adhesive layer is provided on the surface of the packaging film facing away from the electrode assembly. The adhesive layer includes a lipid compound, and the tensile fracture elongation of the packaging film is The tensile fracture elongation of the part of the housing provided with the adhesive layer is

[0006] In the above technical solution, by providing an adhesive layer on the surface of the packaging film facing away from the electrode assembly, the adhesive layer includes a lipid compound, the housing includes the adhesive layer and the packaging film, and the tensile fracture elongation of the part of the housing provided with the adhesive layer When the housing is damaged by an external force, it will break in advance, and the extension of the housing is small, which is conducive to reducing the possibility of the housing being extended to the electrode plate by the external force, and further reducing the possibility of the aluminum layer of the housing contacting the electrode plate to cause a short circuit.

[0007] In some preferred embodiments, the adhesive layer includes a resin compound, which is beneficial to further reduce the tensile fracture elongation of the part of the housing provided with the adhesive layer.

[0008] In some preferred embodiments, the resin compound includes at least one of epoxy resin and phenolic resin, which is beneficial to further reduce the tensile fracture elongation of the part of the housing provided with the adhesive layer.

[0009] In some preferred embodiments, the adhesive layer further includes a curing agent for the resin compound. The curing agent can connect the molecules or polymer chains of the resin compound to form a more stable network structure, thereby increasing the strength and hardness of the adhesive layer.

[0010] In some preferred embodiments, the curing agent is an amine compound or an acid anhydride compound, which is beneficial to the formation of a more stable network structure between the curing agent and the resin compound, thereby increasing the strength and hardness of the adhesive layer.

[0011] In some preferred embodiments, the curing agent includes at least one of aliphatic amine, aromatic amine, modified amine, and maleic anhydride, which is beneficial to the formation of a more stable network structure between the curing agent and the resin compound, thereby increasing the strength and hardness of the adhesive layer.

[0012] In some preferred embodiments, the mass percentage of the curing agent in the adhesive layer is 5% to 20%. When the mass percentage of the curing agent in the adhesive layer < 5%, the curing reaction between the resin compound and the curing agent will be insufficient. By setting the mass percentage of the curing agent in the adhesive layer ≥ 5%, it is beneficial to improve the sufficiency of the curing reaction between the resin compound and the curing agent. When the mass percentage of the curing agent > 20%, the curing agent is in excess, which will reduce the internal cohesion of the housing, and the tensile fracture elongation of the part of the housing provided with the adhesive layer will increase, resulting in a more obvious short-circuit problem of the secondary battery. By setting the mass percentage of the curing agent in the adhesive layer ≤ 20%, it is beneficial to improve the internal cohesion of the housing, beneficial to reduce the tensile fracture elongation of the part of the housing provided with the adhesive layer, and further beneficial to improve the short-circuit problem of the secondary battery.

[0013] In some preferred embodiments, the adhesive layer includes acrylate, and the acrylate can be used without adding a curing agent, which is beneficial to improving the simplicity of preparing the adhesive layer.

[0014] In some preferred embodiments, along the length direction of the electrode assembly, the packaging film includes a first part, a second part, and a third part connected in sequence. Along the width direction of the electrode assembly, the second part includes a first sub - part, a second sub - part, and a third sub - part connected in sequence. A glue layer is provided on the surface of the second sub - part facing away from the electrode assembly. Along the length direction of the electrode assembly, the length of the first part is L1, and the length of the third part is L2, where 1 mm ≤ L1 ≤ 20 mm and 1 mm ≤ L2 ≤ 20 mm. The second part is the middle area of the packaging film, and the first part and the third part are the head and tail areas of the packaging film. Since the head and tail areas of the packaging film are easily collided and worn, if the tensile fracture elongation rate of the head and tail areas of the packaging film is reduced, the head and tail areas of the packaging film are easily damaged. By not providing a glue layer on the surfaces of the first part and the third part facing away from the electrode assembly, and defining the length of the first part in the length direction of the electrode assembly to be 1 mm to 20 mm, the possibility of the glue layer adhering to the first part can be reduced, and the possibility of the first part being damaged can be reduced. Defining the length of the third part in the length direction of the electrode assembly to be 1 mm to 20 mm can reduce the possibility of the glue layer adhering to the third part and the possibility of the third part being damaged. Along the width direction of the electrode assembly, the second sub - part is the middle area of the packaging film, and the first sub - part and the third sub - part are the side areas of the packaging film. Since the side areas of the packaging film are easily collided and worn, if the tensile fracture elongation rate of the side areas of the packaging film is reduced, the side areas of the packaging film are easily damaged. By not providing a glue layer on the surfaces of the first sub - part and the third sub - part facing away from the electrode assembly, the possibility of the first sub - part and the third sub - part being damaged can be reduced.

[0015] In some preferred embodiments, a glue layer is provided on the surface of the first sub - part facing away from the electrode assembly. The first sub - part is the side area of the packaging film. The side area is less likely to be collided and worn compared to the head and tail areas. Therefore, a glue layer can be provided on the surface of the first sub - part facing away from the electrode assembly to reduce the tensile fracture elongation rate of the first sub - part.

[0016] In some preferred embodiments, a glue layer is provided on the surface of the third sub - part facing away from the electrode assembly. The third sub - part is the side area of the packaging film. The side area is less likely to be collided and worn compared to the head and tail areas. Therefore, a glue layer can be provided on the surface of the third sub - part facing away from the electrode assembly to reduce the tensile fracture elongation rate of the third sub - part.

[0017] In some preferred embodiments, along the width direction of the electrode assembly, the first part includes a first corner portion, a first middle portion, and a second corner portion that are sequentially connected. A glue layer is provided on the surface of the first middle portion facing away from the electrode assembly. Along the width direction of the electrode assembly, the width of the first corner portion is W1, and the width of the second corner portion is W2, where 1 mm ≤ W1 ≤ 20 mm and 1 mm ≤ W2 ≤ 20 mm. Since the corners of the packaging film are easily collided and worn, if the tensile fracture elongation rate of the corners of the packaging film is reduced, the corners of the packaging film are prone to breakage. No glue layer is provided on the surfaces of the first corner portion and the second corner portion facing away from the electrode assembly, which can reduce the possibility of breakage of the first corner portion and the second corner portion. Defining the length of the first corner portion in the width direction of the electrode assembly to be 1 mm to 20 mm can reduce the possibility of the glue layer adhering to the first corner portion and can reduce the possibility of breakage of the first corner portion. Defining the length of the second corner portion in the width direction of the electrode assembly to be 1 mm to 20 mm can reduce the possibility of the glue layer adhering to the second corner portion and can reduce the possibility of breakage of the second corner portion. Herein, the corner of the packaging film refers to the area near the intersection of each adjacent side of the packaging film. Since an angle is formed between two adjacent sides, the area near the intersection is called the corner. Taking a cuboid-shaped packaging film as an example, the outer surface of the packaging film is a rectangle, so it has 4 corners, and the 4 corners are respectively located near the intersection of each adjacent two sides of the rectangle. The cuboid-shaped packaging film has a total of 8 corners.

[0018] In some preferred embodiments, along the thickness direction of the electrode assembly, the shape of the projection of the first corner portion can be one of a square, a triangle, a sector, a polygon, or an irregular shape, which can meet various processing methods.

[0019] In some preferred embodiments, along the thickness direction of the electrode assembly, the shape of the projection of the second corner portion can be one of a square, a triangle, a sector, a polygon, or an irregular shape, which can meet various processing methods.

[0020] In some preferred embodiments, along the width direction of the electrode assembly, the third part includes a third corner portion, a second middle portion, and a fourth corner portion that are sequentially connected. A glue layer is provided on the surface of the second middle portion facing away from the electrode assembly. Along the width direction of the electrode assembly, the width of the third corner portion is W3, and the width of the fourth corner portion is W4, where 1 mm ≤ W3 ≤ 20 mm and 1 mm ≤ W4 ≤ 20 mm. No glue layer is provided on the surfaces of the third corner portion and the fourth corner portion facing away from the electrode assembly, which can reduce the possibility of damage to the third corner portion and the fourth corner portion. Defining the length of the third corner portion in the width direction of the electrode assembly to be 1 mm to 20 mm can reduce the possibility of the glue layer adhering to the third corner portion and reduce the possibility of damage to the third corner portion. Defining the length of the fourth corner portion in the width direction of the electrode assembly to be 1 mm to 20 mm can reduce the possibility of the glue layer adhering to the fourth corner portion and reduce the possibility of damage to the fourth corner portion.

[0021] In some preferred embodiments, a tab is connected to the electrode assembly. Along the thickness direction of the electrode assembly, the projection of the tab does not overlap with the projection of the glue layer. By setting the projection of the tab and the projection of the glue layer not to overlap along the thickness direction of the electrode assembly, the possibility of the housing bulging due to the tab and increasing the thickness of the secondary battery can be reduced.

[0022] In some preferred embodiments, the thickness of the glue layer is 1 μm to 60 μm. The greater the thickness of the glue layer, the lower the tensile fracture elongation rate of the part of the housing provided with the glue layer. When the thickness of the glue layer < 1 μm, the reduction of the tensile fracture elongation rate of the part of the housing provided with the glue layer is not obvious. By setting the thickness of the glue layer ≥ 1 μm, the tensile fracture elongation rate of the part of the housing provided with the glue layer can be further reduced. However, the greater the thickness of the glue layer, the more energy density the secondary battery loses. When the thickness of the glue layer is 60 μm, the secondary battery has a good needle penetration rate. Continuing to increase the thickness of the glue layer, the reduction of the tensile fracture elongation rate of the part of the housing provided with the glue layer is not obvious, and more energy density of the secondary battery will be lost. Therefore, considering the tensile fracture elongation rate of the part of the housing provided with the glue layer and the energy density of the secondary battery, it is preferred that the thickness of the glue layer ≤ 60 μm.

[0023] In some preferred embodiments, the glue layer further includes inorganic fillers, which can improve the tensile strength of the glue layer and thus improve the protection effect of the glue layer on the packaging film.

[0024] In some preferred embodiments, the inorganic filler includes glass fiber, and the mass percentage of the glass fiber in the adhesive layer is 10% to 50%. When the inorganic filler in the adhesive layer is glass fiber, when the mass percentage of the inorganic filler ≥ 10%, the tensile strength of the adhesive layer can be further improved. However, the larger the mass percentage of the inorganic filler, the worse the coating uniformity of the adhesive layer. Therefore, considering the tensile strength of the adhesive layer and the coating uniformity of the adhesive layer, it is preferred that the mass percentage of the inorganic filler ≤ 50%.

[0025] In some preferred embodiments, the inorganic filler includes silica, and the mass percentage of the silica in the adhesive layer is 5% to 30%. When the inorganic filler in the adhesive layer is silica, when the mass percentage of the inorganic filler ≥ 5%, the tensile strength of the adhesive layer can be further improved. However, the larger the mass percentage of the inorganic filler, the worse the coating uniformity of the adhesive layer. Therefore, considering the tensile strength of the adhesive layer and the coating uniformity of the adhesive layer, it is preferred that the mass percentage of the inorganic filler ≤ 30%.

[0026] In some preferred embodiments, the larger it is, the lower the tensile fracture elongation of the part of the housing provided with the adhesive layer will be, when, the thickness of the adhesive layer is easily < 1 μm, and the tensile fracture elongation of the part of the housing provided with the adhesive layer is relatively high. By setting the thickness of the adhesive layer can ≥ 1 μm, and the tensile fracture elongation of the part of the housing provided with the adhesive layer can be reduced. when, the thickness of the adhesive layer is easily > 60 μm. Continuing to increase the reduction of the tensile fracture elongation of the part of the housing provided with the adhesive layer is not obvious, and it is easy to lose more energy density of the secondary battery. By setting the thickness of the adhesive layer can ≤ 60 μm, and the energy density of the secondary battery can be improved.

[0027] In some preferred embodiments, the packaging film includes a first polymer layer, a first metal layer, a second polymer layer, and a third polymer layer stacked in sequence, and an adhesive layer is provided on the surface of the third polymer layer facing away from the second polymer layer. The third polymer layer includes polyamide, which can improve the strength of the packaging film.

[0028] In a second aspect, the present application also proposes an electronic device, including the secondary battery according to any one of the embodiments of the first aspect above.

[0029] Thirdly, the present application also provides a manufacturing method for a secondary battery, which is used to prepare the secondary battery according to any embodiment of the first aspect above, including: providing a packaging film and an electrode assembly, and wrapping the packaging film around the outer surface of the electrode assembly. Providing an adhesive layer, and coating the adhesive layer on the surface of the packaging film facing away from the electrode assembly. Since the packaging film needs to be dimpled before wrapping the electrode assembly, the packaging film requires a certain elongation at break. By providing the adhesive layer after the packaging film wraps the electrode assembly, the housing includes the adhesive layer and the packaging film, which can reduce the elongation at break of the part of the housing provided with the adhesive layer, without affecting the elongation at break of the packaging film before wrapping the electrode assembly, so that the packaging film can meet the dimple requirement.

[0030] Additional aspects and advantages of the embodiments of the present application will be described, shown, or illustrated in part in the subsequent description, or through the implementation of the embodiments of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] One or more embodiments are exemplarily illustrated by the corresponding drawings. These exemplary illustrations do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings are represented as similar elements, unless otherwise stated, the dimensions in the drawings do not constitute a proportional limitation.

[0032] Figure 1 Schematic diagram of the structure of a secondary battery according to some embodiments of the present application;

[0033] Figure 2 Schematic diagram of the structure of an electrode assembly according to some embodiments of the present application;

[0034] Figure 3 Schematic diagram of the structure of a secondary battery according to some embodiments of the present application;

[0035] Figure 4 Schematic diagram of the structure of a secondary battery according to some embodiments of the present application;

[0036] Figure 5 Schematic diagram of the structure of a secondary battery according to some embodiments of the present application;

[0037] Figure 6 Schematic diagram of the structure of a secondary battery according to some embodiments of the present application;

[0038] Figure 7 Schematic diagram of the structure of a secondary battery according to some embodiments of the present application;

[0039] Figure 8 Schematic diagram of the structure of a secondary battery according to some embodiments of the present application;

[0040] Figure 9 Schematic diagram of the structure of a secondary battery according to some embodiments of the present application;

[0041] Figure 10 Schematic structural diagram of a secondary battery according to some embodiments of the present application;

[0042] Figure 11 Schematic structural diagram of a packaging film and an adhesive layer according to some embodiments of the present application.

[0043] Description of reference numerals:

[0044] 100. Secondary battery; 10. Housing; 11. Packaging film; 111. First polymer layer; 112. First metal layer; 113. Second polymer layer; 114. Third polymer layer; 115. First part; 1151. First corner part; 1152. First middle part; 1153. Second corner part; 116. Second part; 1161. First sub - part; 1162. Second sub - part; 1163. Third sub - part; 117. Third part; 1171. Third corner part; 1172. Second middle part; 1173. Fourth corner part; 12. Adhesive layer; 20. Electrode assembly; 20a. Tab; 21. Positive electrode sheet; 22. Negative electrode sheet; 23. Separator; X. Length direction of the electrode assembly; Y. Width direction of the electrode assembly; Z. Thickness direction of the electrode assembly. Detailed implementation manners

[0045] To make the objectives, 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 with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application.

[0046] Referring to "embodiments" in the present application means that specific features, structures, or characteristics described in connection with the embodiments can be included in at least one embodiment of the present application. The phrase appears in various positions in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments.

[0047] In the description of the embodiments of the present application, technical terms such as "first" and "second" are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity, specific order, or primary - secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "a plurality of" is more than two, unless otherwise specifically defined.

[0048] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this article generally represents an "or" relationship between the associated objects before and after.

[0049] The term "vertical" is used to describe the ideal state between two components. In the actual production or use state, there can be a state approximately vertical between two components. For example, in combination with numerical descriptions, vertical can refer to the included angle range between two straight lines being between 90±10°, vertical can also refer to the dihedral angle range between two planes being between 90±10°, and vertical can further refer to the included angle range between a straight line and a plane being between 90±10°. The two components described as "vertical" may not be absolutely straight lines or planes, and can also be approximately straight lines or planes. From a macroscopic perspective, as long as the overall extension direction is a straight line or a plane, the components can be considered "straight lines" or "planes".

[0050] In different embodiments of the present application described below, the technical features involved can be combined with each other as long as they do not conflict with each other.

[0051] In a first aspect, an embodiment of the present application provides a secondary battery 100. Please refer to Figure 1 . The secondary battery 100 includes a housing 10, an electrode assembly 20, and a tab 20a. The housing 10 can accommodate the electrode assembly 20 and an electrolyte (not shown in the figure). The electrolyte infiltrates the electrode assembly 20 within the housing 10. The tab 20a is connected to the electrode assembly 20, and the tab 20a extends out of the housing 10 in the length direction X of the electrode assembly 20 to assist the electrode assembly 20 in performing energy transfer with an external electronic device.

[0052] Regarding the above electrode assembly 20, please refer to Figure 2 . Figure 2 shows a stacked structure of the electrode assembly 20. The electrode assembly 20 includes a negative electrode sheet 22, a positive electrode sheet 21, and a separator 23. In the thickness direction Z of the electrode assembly 20, the positive electrode sheet 21 and the negative electrode sheet 22 are alternately stacked, and a separator 23 is provided between adjacent positive electrode sheet 21 and negative electrode sheet 22. The separator 23 is used to insulate and separate the positive electrode sheet 21 and the negative electrode sheet 22. In the embodiment of the present application, taking the electrode assembly 20 as a stacked structure as an example for illustration, in some other embodiments, the electrode assembly 20 can also be a wound structure and other structures. For example, after the positive electrode sheet 21, the separator 23, and the negative electrode sheet 22 are stacked in sequence, they are then wound to form a wound electrode assembly 20. Among them, the thickness direction Z of the electrode assembly 20 is perpendicular to the length direction X of the electrode assembly 20.

[0053] Please refer to Figure 3 and Figure 4 . The housing 10 includes a packaging film 11, and the packaging film 11 wraps around the outer surface of the electrode assembly 20. When the secondary battery 100 is damaged by an external force, the packaging film 11 is easily extended to the electrode plate by the external force, resulting in the aluminum layer of the packaging film 11 coming into contact with the electrode plate and thus causing a short circuit.

[0054] To improve the above problems, in the embodiments of the present application, the housing 10 further includes an adhesive layer 12. The adhesive layer 12 is provided on the surface of the packaging film 11 facing away from the electrode assembly 20. The adhesive layer 12 includes a lipid compound, and the tensile fracture elongation rate of the packaging film 11 is The tensile fracture elongation rate of the part of the housing 10 provided with the adhesive layer 12 is By providing the adhesive layer 12 on the surface of the packaging film 11 facing away from the electrode assembly 20, the adhesive layer 12 includes a lipid compound, the housing 10 includes the adhesive layer 12 and the packaging film 11, and the tensile fracture elongation rate of the part of the housing 10 provided with the adhesive layer 12 When the housing 10 is damaged by an external force, it will break in advance, and the extension of the housing 10 is small, which is beneficial to reducing the possibility that the housing 10 is extended to the pole piece by an external force, and thus can reduce the possibility of short circuit between the aluminum layer of the housing 10 and the pole piece.

[0055] In some embodiments, the thickness H of the adhesive layer 12 is 1 μm to 60 μm. The greater the thickness of the adhesive layer 12, the lower the tensile fracture elongation rate of the part of the housing 10 provided with the adhesive layer 12. When the thickness of the adhesive layer 12 < 1 μm, the reduction of the tensile fracture elongation rate of the part of the housing 10 provided with the adhesive layer 12 is not obvious. By setting the thickness of the adhesive layer 12 ≥ 1 μm, the tensile fracture elongation rate of the part of the housing 10 provided with the adhesive layer 12 can be further reduced. However, the greater the thickness of the adhesive layer 12, the more energy density the secondary battery 100 loses. When the thickness of the adhesive layer 12 is 60 μm, the secondary battery 100 has a good needle penetration rate. Continuing to increase the thickness of the adhesive layer 12, the reduction of the tensile fracture elongation rate of the part of the housing 10 provided with the adhesive layer 12 is not obvious, and more energy density of the secondary battery 100 will be lost. Therefore, considering the tensile fracture elongation rate of the part of the housing 10 provided with the adhesive layer 12 and the energy density of the secondary battery 100, it is preferred that the thickness of the adhesive layer 12 ≤ 60 μm.

[0056] In some embodiments, Preferably, In some embodiments, It can be 3.2%, 5%, 8.8%, 10%, 15%, 20%, 24.9%, 25%, 29.4%, 30%, 35%, 40%, 45%, 50%, 54.3%, 55%, 59.8%, 60%, 64.9% or a value within the range composed of any two of these values or a value within the range composed of any two of these values. The greater it is, the lower the tensile fracture elongation rate of the part of the housing 10 provided with the adhesive layer 12 will be, When it is, the thickness of the adhesive layer 12 is easily < 1 μm, and the tensile fracture elongation rate of the part of the housing 10 provided with the adhesive layer 12 is relatively high. By setting The thickness of the adhesive layer 12 can be ≥1 μm, and it can reduce the tensile fracture elongation of the part of the housing 10 provided with the adhesive layer 12. When it is, the thickness of the adhesive layer 12 is liable to be >60 μm. Continuing to increase the reduction of the tensile fracture elongation of the part of the housing 10 provided with the adhesive layer 12 is not obvious, and it is liable to lose more energy density of the secondary battery 100. By setting the thickness of the adhesive layer 12 can be ≤60 μm, which can improve the energy density of the secondary battery 100.

[0057] In some embodiments, the adhesive layer 12 includes a resin compound, which is beneficial to further reducing the tensile fracture elongation of the part of the housing 10 provided with the adhesive layer 12.

[0058] In some embodiments, the resin compound includes at least one of epoxy resin and phenolic resin, which is beneficial to further reducing the tensile fracture elongation of the part of the housing 10 provided with the adhesive layer 12.

[0059] In some embodiments, the adhesive layer 12 further includes a curing agent for the resin compound. The curing agent can connect the molecules or polymer chains of the resin compound to form a more stable network structure, thereby increasing the strength and hardness of the adhesive layer 12.

[0060] In some embodiments, the curing agent is an amine compound or an acid anhydride compound, which is beneficial to the curing agent and the resin compound forming a more stable network structure, thereby increasing the strength and hardness of the adhesive layer 12.

[0061] In some embodiments, the curing agent includes at least one of aliphatic amine, aromatic amine, modified amine, and maleic anhydride, which is beneficial to the curing agent and the resin compound forming a more stable network structure, thereby increasing the strength and hardness of the adhesive layer 12.

[0062] In some embodiments, the mass percentage of the curing agent in the adhesive layer 12 is 2% to 25%, preferably, the mass percentage of the curing agent in the adhesive layer 12 is 5% to 20%. In some embodiments, the mass percentage of the curing agent in the adhesive layer 12 can be 2%, 5%, 8%, 8.3%, 10%, 13%, 15%, 18%, 20%, 23%, 25% or a range composed of any two of these values or a value within a range composed of any two of these values. When the mass percentage of the curing agent in the adhesive layer 12 < 5%, the curing reaction between the resinous compound and the curing agent will be insufficient. By setting the mass percentage of the curing agent in the adhesive layer 12 ≥ 5%, it is beneficial to improve the sufficiency of the curing reaction between the resinous compound and the curing agent. When the mass percentage of the curing agent > 20%, the curing agent is in excess, which will reduce the cohesive force of the housing 10, and the tensile fracture elongation of the part of the housing 10 provided with the adhesive layer 12 will increase, resulting in a more obvious short-circuit problem of the secondary battery 100. By setting the mass percentage of the curing agent in the adhesive layer 12 ≤ 20%, it is beneficial to increase the cohesive force of the housing 10, beneficial to reduce the tensile fracture elongation of the part of the housing 10 provided with the adhesive layer 12, and thus beneficial to improve the short-circuit problem of the secondary battery 100.

[0063] In some embodiments, the adhesive layer 12 includes acrylate, and the acrylate can be used without adding a curing agent, which is beneficial to improving the simplicity of preparing the adhesive layer 12.

[0064] In some embodiments, please refer to Figure 3 、 Figure 4 and Figure 5, along the length direction X of the electrode assembly 20, the packaging film 11 includes a first part 115, a second part 116, and a third part 117 that are sequentially connected. Along the width direction Y of the electrode assembly 20, the second part 116 includes a first sub-part 1161, a second sub-part 1162, and a third sub-part 1163 that are sequentially connected. A glue layer 12 is provided on the surface of the second sub-part 1162 facing away from the electrode assembly 20. Along the length direction X of the electrode assembly 20, the length of the first part 115 is L1, and the length of the third part 117 is L2, where 1 mm ≤ L1 ≤ 20 mm and 1 mm ≤ L2 ≤ 20 mm. The second part 116 is the middle area of the packaging film 11, and the first part 115 and the third part 117 are the head and tail areas of the packaging film 11. Since the head and tail areas of the packaging film 11 are easily collided and worn, if the tensile fracture elongation rate of the head and tail areas of the packaging film 11 is reduced, the head and tail areas of the packaging film 11 are easily damaged. By not providing the glue layer 12 on the surfaces of the first part 115 and the third part 117 facing away from the electrode assembly 20 and defining the length of the first part 115 in the length direction X of the electrode assembly 20 to be 1 mm to 20 mm, the possibility of the glue layer 12 adhering to the first part 115 can be reduced, and the possibility of the first part 115 being damaged can be reduced. Defining the length of the third part 117 in the length direction X of the electrode assembly 20 to be 1 mm to 20 mm can reduce the possibility of the glue layer 12 adhering to the third part 117 and can reduce the possibility of the third part 117 being damaged. Along the width direction Y of the electrode assembly 20, the second sub-part 1162 is the middle area of the packaging film 11, and the first sub-part 1161 and the third sub-part 1163 are the side areas of the packaging film 11. Since the side areas of the packaging film 11 are easily collided and worn, if the tensile fracture elongation rate of the side areas of the packaging film 11 is reduced, the side areas of the packaging film 11 are easily damaged. By not providing the glue layer 12 on the surfaces of the first sub-part 1161 and the third sub-part 1163 facing away from the electrode assembly 20, the possibility of the first sub-part 1161 and the third sub-part 1163 being damaged can be reduced. Among them, the width direction Y, the thickness direction Z, and the length direction X of the electrode assembly 20 are perpendicular to each other in pairs.

[0065] In some embodiments, please refer to Figure 6 , a glue layer 12 is provided on the surface of the first sub-part 1161 facing away from the electrode assembly 20. The first sub-part 1161 is the side area of the packaging film 11. The side area is less likely to be collided and worn compared to the head and tail areas. Therefore, a glue layer 12 can be provided on the surface of the first sub-part 1161 facing away from the electrode assembly 20 to reduce the tensile fracture elongation rate of the first sub-part 1161.

[0066] In some embodiments, an adhesive layer 12 is disposed on the surface of the third sub - portion 1163 facing away from the electrode assembly 20. The third sub - portion 1163 is a side region of the packaging film 11. The side region is less likely to be collided and worn compared to the head and tail regions. Therefore, the adhesive layer 12 can be disposed on the surface of the third sub - portion 1163 facing away from the electrode assembly 20 to reduce the tensile fracture elongation rate of the third sub - portion 1163.

[0067] In some embodiments, please refer to Figure 7 and Figure 8 , along the width direction Y of the electrode assembly 20, the first part 115 includes a first corner portion 1151, a first middle portion 1152, and a second corner portion 1153 that are connected in sequence. An adhesive layer 12 is disposed on the surface of the first middle portion 1152 facing away from the electrode assembly 20. Along the width direction Y of the electrode assembly 20, the width of the first corner portion 1151 is W1, and the width of the second corner portion 1153 is W2, where 1 mm ≤ W1 ≤ 20 mm and 1 mm ≤ W2 ≤ 20 mm. Since the corners of the packaging film 11 are easily collided and worn, if the tensile fracture elongation rate of the corners of the packaging film 11 is reduced, the corners of the packaging film 11 are likely to be damaged. The adhesive layer 12 is not disposed on the surfaces of the first corner portion 1151 and the second corner portion 1153 facing away from the electrode assembly 20, which can reduce the possibility of damage to the first corner portion 1151 and the second corner portion 1153. Defining the length of the first corner portion 1151 in the width direction Y of the electrode assembly 20 to be 1 mm to 20 mm can reduce the possibility of the adhesive layer 12 adhering to the first corner portion 1151 and can reduce the possibility of damage to the first corner portion 1151. Defining the length of the second corner portion 1153 in the width direction Y of the electrode assembly 20 to be 1 mm to 20 mm can reduce the possibility of the adhesive layer 12 adhering to the second corner portion 1153 and can reduce the possibility of damage to the second corner portion 1153. Herein, the corner of the packaging film 11 refers to the region near the intersection of each adjacent side of the packaging film 11. Since an angle is formed between two adjacent sides, the region near the intersection is called a corner. Taking the packaging film 11 in the shape of a cuboid as an example, the outer surface of the packaging film 11 is rectangular, so it has 4 corners, and the 4 corners are respectively located near the intersection of each adjacent two sides of the rectangle. The cuboid - shaped packaging film 11 has a total of 8 corners.

[0068] In some embodiments, along the thickness direction Z of the electrode assembly 20, the shape of the projection of the first corner portion 1151 can be one of a square, a triangle, a sector, a polygon, or an irregular shape, which can meet various processing methods.

[0069] In some embodiments, along the thickness direction Z of the electrode assembly 20, the shape of the projection of the second corner portion 1153 can be one of a square, a triangle, a sector, a polygon, or an irregular shape, which can meet various processing methods.

[0070] In some embodiments, please refer to Figure 7 and Figure 9 , along the width direction Y of the electrode assembly 20, the third part 117 includes a third corner part 1171, a second middle part 1172, and a fourth corner part 1173 that are connected in sequence. An adhesive layer 12 is provided on the surface of the second middle part 1172 facing away from the electrode assembly 20. Along the width direction Y of the electrode assembly 20, the width of the third corner part 1171 is W3, and the width of the fourth corner part 1173 is W4, where 1 mm ≤ W3 ≤ 20 mm and 1 mm ≤ W4 ≤ 20 mm. No adhesive layer 12 is provided on the surfaces of the third corner part 1171 and the fourth corner part 1173 facing away from the electrode assembly 20, which can reduce the possibility of breakage of the third corner part 1171 and the fourth corner part 1173. Defining the length of the third corner part 1171 in the width direction Y of the electrode assembly 20 to be 1 mm to 20 mm can reduce the possibility of the adhesive layer 12 adhering to the third corner part 1171 and can reduce the possibility of breakage of the third corner part 1171. Defining the length of the fourth corner part 1173 in the width direction Y of the electrode assembly 20 to be 1 mm to 20 mm can reduce the possibility of the adhesive layer 12 adhering to the fourth corner part 1173 and can reduce the possibility of breakage of the fourth corner part 1173.

[0071] In some embodiments, please refer to Figure 10 , the electrode assembly 20 is connected with a tab 20a, and along the thickness direction Z of the electrode assembly 20, the projection of the tab 20a does not overlap with the projection of the adhesive layer 12. By setting the projection of the tab 20a not to overlap with the projection of the adhesive layer 12 along the thickness direction Z of the electrode assembly 20, the possibility that the thickness of the secondary battery 100 increases due to the protrusion of the tab 20a on the housing 10 can be reduced.

[0072] In some embodiments, the adhesive layer 12 further includes an inorganic filler, and the inorganic filler can improve the tensile strength of the adhesive layer 12, and thus can improve the protection effect of the adhesive layer 12 on the packaging film 11.

[0073] In some embodiments, the inorganic filler includes glass fiber, and the mass percentage of the glass fiber in the adhesive layer 12 is 5% to 60%. Preferably, the mass percentage of the glass fiber in the adhesive layer 12 is 10% to 50%. In some embodiments, the mass percentage of the glass fiber in the adhesive layer 12 can be 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, or a range composed of any two of these values, or a value within the range composed of any two of these values. When the inorganic filler in the adhesive layer 12 is glass fiber, when the mass percentage of the inorganic filler ≥ 10%, the tensile strength of the adhesive layer 12 can be further improved. However, the larger the mass percentage of the inorganic filler, the worse the coating uniformity of the adhesive layer 12. Therefore, considering the tensile strength of the adhesive layer 12 and the coating uniformity of the adhesive layer 12, it is preferred that the mass percentage of the inorganic filler ≤ 50%.

[0074] In some embodiments, the inorganic filler includes silica, and the mass percentage of the silica in the adhesive layer 12 is 2% to 40%. Preferably, the mass percentage of the silica in the adhesive layer 12 is 5% to 30%. In some embodiments, the mass percentage of the silica in the adhesive layer 12 can be 2%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, or a range composed of any two of these values, or a value within the range composed of any two of these values. When the inorganic filler in the adhesive layer 12 is silica, when the mass percentage of the inorganic filler ≥ 5%, the tensile strength of the adhesive layer 12 can be further improved. However, the larger the mass percentage of the inorganic filler, the worse the coating uniformity of the adhesive layer 12. Therefore, considering the tensile strength of the adhesive layer 12 and the coating uniformity of the adhesive layer 12, it is preferred that the mass percentage of the inorganic filler ≤ 30%.

[0075] In some embodiments, please refer to Figure 9 and Figure 11 , the packaging film 11 includes a first polymer layer 111, a first metal layer 112, a second polymer layer 113, and a third polymer layer 114 that are stacked in sequence. A glue layer 12 is provided on the surface of the third polymer layer 114 facing away from the second polymer layer 113. The first polymer layer 111 includes polypropylene to make the packaging film 11 easy to encapsulate. The first metal layer 112 includes aluminum to enhance the plasticity of the packaging film 11. The second polymer layer 113 includes polyurethane to enhance the adhesion performance of the second polymer layer 113. The third polymer layer 114 includes polyamide, which can improve the strength of the packaging film 11.

[0076] In a second aspect of the present application, an electronic device is further provided, including a secondary battery 100 as in any embodiment of the first aspect above. The electronic device in the embodiments of the present application is not particularly limited, and it may be any electronic device known in the prior art. For example, the electronic device includes but is not limited to a Bluetooth headset, a mobile phone, a tablet computer, a laptop computer, an electric toy, an electric tool, an electric vehicle, an electric car, a ship, a spacecraft, and the like. Among them, the electric toy may include a stationary or mobile electric toy, for example, a game console, an electric vehicle toy, an electric ship toy, an electric aircraft toy, and the like, and the spacecraft may include an airplane, a rocket, a space shuttle, a spaceship, and the like.

[0077] In a third aspect of the present application, a manufacturing method of a secondary battery 100 is further provided, for preparing the secondary battery 100 as in any embodiment of the first aspect above, including: providing a packaging film 11 and an electrode assembly 20, and wrapping the packaging film 11 around the outer surface of the electrode assembly 20. Providing an adhesive layer 12, and coating the adhesive layer 12 on the surface of the packaging film 11 facing away from the electrode assembly 20. Since the packaging film 11 needs to be dimpled before wrapping the electrode assembly 20, the packaging film 11 requires a certain elongation at break. By providing the adhesive layer 12 after the packaging film 11 wraps the electrode assembly 20, the housing 10 includes the adhesive layer 12 and the packaging film 11, which can reduce the elongation at break of the part of the housing 10 provided with the adhesive layer 12, without affecting the elongation at break of the packaging film 11 before the packaging film 11 wraps the electrode assembly 20, so that the packaging film 11 can meet the dimple requirement.

[0078] Test part:

[0079] 1. Tensile test of the packaging film:

[0080] Take the packaging film without the adhesive layer as a sample, use a special tensile cutting knife to make a test sample with a length of 70 mm and a width of 15 mm, fix the test sample to the test fixture of a high-speed rail tensile machine, with a tensile speed of 50 ± 0.5 mm / min and a tensile spacing of 50 mm.

[0081] Elongation at break of the packaging film = (displacement at break of the sample / initial length of the sample) × 100%.

[0082] 2. Tensile test of the housing:

[0083] Take the housing as a sample, the housing includes a packaging film and an adhesive layer provided on the surface of the packaging film, use a special tensile cutting knife to make a test sample with a length of 70 mm and a width of 15 mm, fix the test sample to the test fixture of a high-speed rail tensile machine, with a tensile speed of 50 ± 0.5 mm / min and a tensile spacing of 50 mm.

[0084] Elongation at break of the part of the housing provided with the adhesive layer = (displacement at break of the sample / initial length of the sample) × 100%.

[0085] 3. Nail Test:

[0086] First, fully charge the secondary battery. Place the sample flat on the test tabletop. Use a special nail with a diameter of 3 mm, a chamfer of 0.3, a nail tip length of 3 mm, and a nail body length of ≥100 mm to test from the center position of the sample at a speed of 150 ± 1.5 mm / s until the sample is completely pierced.

[0087] Passing criterion: After the test, the secondary battery does not catch fire or explode.

[0088] Example 1

[0089] <Preparation of the positive electrode sheet>:

[0090] Use aluminum foil as the positive electrode current collector. Uniformly coat a layer of lithium cobalt oxide slurry on the surface of the aluminum foil. The slurry composition is a combination of 97.5 wt% lithium cobalt oxide (LiCoO2), 1.0 wt% carbon black (Super P), and 1.5 wt% polyvinylidene fluoride (PVDF). Dry it at 85 °C, and then perform cold pressing, slicing, and slitting to prepare the positive electrode sheet.

[0091] <Preparation of the negative electrode sheet>:

[0092] Use copper foil as the negative electrode current collector. Uniformly coat a layer of graphite slurry on the surface of the copper foil. The slurry composition is a combination of 97.7 wt% artificial graphite, 1.3 wt% sodium carboxymethyl cellulose (CMC), and 1.0 wt% styrene-butadiene rubber (SBR). Dry it at 85 °C, and then perform cold pressing, slicing, and slitting to prepare the negative electrode sheet.

[0093] <Preparation of the electrolyte>:

[0094] Use a solution prepared by mixing lithium salt LiPF6 with a non-aqueous organic solvent (ethylene carbonate (EC): diethyl carbonate (DEC): propylene carbonate (PC): propyl propionate (PP): vinylene carbonate (VC) = 20:30:20:28:2, by mass ratio) at a mass ratio of 8:92 as the electrolyte of the secondary battery.

[0095] <Preparation of the secondary battery>:

[0096] Weld the tabs of the positive electrode sheet and the negative electrode sheet, and then stack the positive electrode sheet and the negative electrode sheet. Separate the positive electrode sheet and the negative electrode sheet with a polyethylene separator to prepare the electrode assembly.

[0097] Use an aluminum-plastic film with a thickness of 103 μm as the packaging film. Wrap the packaging film around the outer surface of the electrode assembly. After top-side sealing, inkjet coding, vacuum drying, injecting the electrolyte, and high-temperature standing, perform formation and capacity measurement to obtain the preliminary secondary battery.

[0098] 83.3wt% epoxy resin and 8.3wt% fatty amine (curing agent) were mixed in air for 3-5min (the mass ratio of 83.3wt% epoxy resin and 8.3wt% fatty amine was about 10:1), and coated on the surface of the packaging film of the preliminary secondary battery away from the electrode assembly, and cured in an oven at 80℃ for 1h to form a glue layer. The thickness of the glue layer is 10μm. Along the length direction of the electrode assembly (the direction in which the tab extends out of the shell), the packaging film includes a first part, a second part and a third part connected in sequence, the length L1 of the first part is 3mm, and the length L2 of the third part is 3mm. The surface of the second part away from the electrode assembly is provided with a glue layer, and the first part and the third part are not provided with a glue layer. Along the width direction of the electrode assembly, the second part includes a first sub-section, a second sub-section and a third sub-section connected in sequence, the length L3 of the first sub-section is 3mm, and the length L2 of the third sub-section is 3mm. The surface of the second sub-section away from the electrode assembly is provided with a glue layer, and the first sub-section and the third sub-section are not provided with a glue layer. The shell includes a glue layer and a packaging film. The length of the secondary battery is 99 mm, and the width of the secondary battery is 66 mm.

[0099] The relevant parameters in Comparative Example 1 and Examples 1 to 7 are shown in Table 1 below.

[0100] The shell of comparative example 1 is only a packaging film and does not include a glue layer. The thickness of the glue layer of embodiments 1 to 7 is different.

[0101] Table 1

[0102]

[0103] Note: “\” in Table 1 means that the parameter is not included.

[0104] According to Table 1, in combination with Comparative Example 1 and Examples 1 to 7, a glue layer is provided on the surface of the packaging film away from the electrode assembly, the glue layer includes a lipid compound, the shell includes the glue layer and the packaging film, and the tensile elongation at break of the portion of the shell where the glue layer is provided is The shell will break prematurely when damaged by external force. The shell has a small elongation, which helps reduce the possibility of the shell being extended to the pole piece by external force, thereby reducing the possibility of short circuit between the aluminum layer of the shell and the pole piece, thus improving the puncture pass rate.

[0105] Combined with Examples 1 to 7, it can be seen that the greater the thickness of the adhesive layer, the lower the tensile fracture elongation of the part of the housing provided with the adhesive layer, and the higher the nail penetration rate of the secondary battery. When the thickness of the adhesive layer < 1 μm, the decrease in the tensile fracture elongation of the part of the housing provided with the adhesive layer is not obvious. By setting the thickness of the adhesive layer ≥ 1 μm, the tensile fracture elongation of the part of the housing provided with the adhesive layer can be further reduced, thereby further improving the nail penetration rate of the secondary battery. However, the greater the thickness of the adhesive layer, the more energy density the secondary battery loses. When the thickness of the adhesive layer is 60 μm, the secondary battery has a good nail penetration rate. Continuing to increase the thickness of the adhesive layer, the improvement of the nail penetration rate of the secondary battery is not obvious, and more energy density of the secondary battery will be lost. Therefore, considering the nail penetration rate of the secondary battery and the energy density of the secondary battery comprehensively, it is preferred that the thickness of the adhesive layer ≤ 60 μm.

[0106] Combined with Examples 1 to 7, it can be seen that the tensile fracture elongation of the packaging film is The tensile fracture elongation of the part of the housing provided with the adhesive layer is The greater it is, the higher the nail penetration rate of the secondary battery. When, the thickness of the adhesive layer is easily < 1 μm, and the nail penetration rate of the secondary battery is relatively low. By setting the thickness of the adhesive layer can be ≥ 1 μm, and the nail penetration rate of the secondary battery can be improved. When, the thickness of the adhesive layer is easily > 60 μm. Continuing to increase the nail penetration rate of the secondary battery is not significantly improved, and more energy density of the secondary battery is easily lost. By setting the thickness of the adhesive layer can be ≤ 60 μm, and the energy density of the secondary battery can be improved.

[0107] The relevant parameters in Example 1 and Examples 8 to 11 are shown in Table 2 below.

[0108] Among them, the mass percentages of the curing agent in the adhesive layer of Example 1 and Examples 8 to 11 are different.

[0109] Table 2

[0110]

[0111] According to Table 2 above, in combination with Example 1 and Examples 8 to 11, it can be seen that when the mass percentage of the curing agent in the adhesive layer is 5% to 20%, the part of the housing provided with the adhesive layer has a lower tensile fracture elongation rate, and the secondary battery has a higher puncture passing rate. When the mass percentage of the curing agent in the adhesive layer < 5%, the curing reaction of the lipid compound and the curing agent will be insufficient. When the mass percentage of the curing agent > 20%, the curing agent will be in excess, which will reduce the cohesive force of the housing, and the tensile fracture elongation rate of the part of the housing provided with the adhesive layer will increase, resulting in a decrease in the puncture passing rate of the secondary battery. Therefore, it is preferred that the mass percentage of the curing agent in the adhesive layer is 5% to 20%.

[0112] The relevant parameters in Example 1 and Examples 12 to 21 are shown in Table 3 below.

[0113] Among them, the inorganic filler in Examples 12 to 16 is glass fiber, and the mass percentage of the inorganic filler in the adhesive layer in Examples 12 to 16 is different.

[0114] The inorganic filler in Examples 17 to 21 is silica, and the mass percentage of the inorganic filler in the adhesive layer in Examples 17 to 21 is different.

[0115] Table 3

[0116]

[0117] Note: “\” in Table 3 indicates that the parameter is not included.

[0118] According to Table 3 above, in combination with Example 1 and Examples 12 to 21, it can be seen that by setting the adhesive layer to include an inorganic filler, the tensile strength of the adhesive layer can be improved, and further the protective effect of the adhesive layer on the packaging film can be improved.

[0119] In combination with Example 1 and Examples 12 to 16, it can be seen that when the inorganic filler in the adhesive layer is glass fiber, when the mass percentage of the inorganic filler ≥ 10%, the tensile strength of the adhesive layer can be further improved. However, the larger the mass percentage of the inorganic filler, the worse the coating uniformity of the adhesive layer. Therefore, considering the tensile strength of the adhesive layer and the coating uniformity of the adhesive layer, it is preferred that the mass percentage of the inorganic filler ≤ 50%.

[0120] In combination with Example 1 and Examples 17 to 21, it can be seen that when the inorganic filler in the adhesive layer is silica, when the mass percentage of the inorganic filler ≥ 5%, the tensile strength of the adhesive layer can be further improved. However, the larger the mass percentage of the inorganic filler, the worse the coating uniformity of the adhesive layer. Therefore, considering the tensile strength of the adhesive layer and the coating uniformity of the adhesive layer, it is preferred that the mass percentage of the inorganic filler ≤ 30%.

[0121] The above are only embodiments of the present application, and do not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made by using the content of the specification and drawings of the present application, or directly or indirectly applied in other related technical fields, shall be equally included in the patent protection scope of the present application.

Claims

1. A secondary battery, comprising a housing and an electrode assembly, wherein the housing comprises a packaging film, and the packaging film is wrapped around the outer surface of the electrode assembly; It is characterized in that The shell also includes a glue layer, the glue layer is arranged on the surface of the packaging film facing away from the electrode assembly, the glue layer includes a lipid compound, the tensile elongation at break of the packaging film is φ1, and the tensile elongation at break of the portion of the shell where the glue layer is arranged is φ2, φ2<φ1.

2. The secondary battery according to claim 1, characterized in that: The glue layer includes a resin compound.

3. The secondary battery according to claim 2, characterized in that: The resin compound includes at least one of epoxy resin and phenolic resin.

4. The secondary battery according to claim 2, characterized in that: The glue layer also includes a curing agent for the resin compound.

5. The secondary battery according to claim 4, characterized in that: The curing agent is an amine compound or an acid anhydride compound.

6. The secondary battery according to claim 5, characterized in that: The curing agent includes at least one of aliphatic amine, aromatic amine, modified amine and maleic anhydride.

7. The secondary battery according to claim 4, characterized in that: The mass percentage of the curing agent in the adhesive layer is 5% to 20%.

8. The secondary battery according to claim 1, characterized in that: The adhesive layer includes acrylate.

9. The secondary battery according to claim 1, characterized in that: Along the length direction of the electrode assembly, the packaging film includes a first part, a second part and a third part connected in sequence; along the width direction of the electrode assembly, the second part includes a first sub-part, a second sub-part and a third sub-part connected in sequence; the surface of the second sub-part facing away from the electrode assembly is provided with the glue layer, and along the length direction of the electrode assembly, the length of the first part is L1, the length of the third part is L2, 1mm≤L1≤20mm, 1mm≤L2≤20mm.

10. The secondary battery according to claim 9, characterized in that: The glue layer is disposed on a surface of the first sub-part facing away from the electrode assembly; and / or the glue layer is disposed on a surface of the third sub-part facing away from the electrode assembly.

11. The secondary battery according to claim 9, characterized in that: Along the width direction of the electrode assembly, the first part includes a first angular portion, a first middle portion and a second angular portion connected in sequence; the surface of the first middle portion facing away from the electrode assembly is provided with the glue layer; along the width direction of the electrode assembly, the width of the first angular portion is W1, the width of the second angular portion is W2, 1mm≤W1≤20mm, 1mm≤W2≤20mm.

12. The secondary battery according to claim 11, characterized in that: Along the thickness direction of the electrode assembly, the projection of the first angular portion may be in the shape of a square, a triangle, a sector, a polygon or an irregular shape; and / or, along the thickness direction of the electrode assembly, the projection of the second angular portion may be in the shape of a square, a triangle, a sector, a polygon or an irregular shape.

13. The secondary battery according to claim 9, characterized in that: Along the width direction of the electrode assembly, the third part includes a third angular portion, a second middle portion and a fourth angular portion connected in sequence; the surface of the second middle portion facing away from the electrode assembly is provided with the glue layer; along the width direction of the electrode assembly, the width of the third angular portion is W3, the width of the fourth angular portion is W4, 1mm≤W3≤20mm, 1mm≤W4≤20mm.

14. The secondary battery according to claim 1, characterized in that: The electrode assembly is connected with a pole ear, and along the thickness direction of the electrode assembly, the projection of the pole ear does not overlap with the projection of the glue layer.

15. The secondary battery according to claim 1, characterized in that: The thickness of the adhesive layer is 1 μm to 60 μm.

16. The secondary battery according to claim 1, characterized in that: The adhesive layer also includes inorganic fillers.

17. The secondary battery according to claim 16, characterized in that: The inorganic filler includes glass fiber, and the mass percentage of the glass fiber in the adhesive layer is 10% to 50%; or, the inorganic filler includes silicon dioxide, and the mass percentage of the silicon dioxide in the adhesive layer is 5% to 30%.

18. The secondary battery according to claim 1, characterized in that: 8.8%≤φ1-φ2≤59.8%.

19. The secondary battery according to claim 1, characterized in that: The packaging film comprises a first polymer layer, a first metal layer, a second polymer layer and a third polymer layer which are stacked in sequence. The adhesive layer is arranged on a surface of the third polymer layer which is away from the second polymer layer. The third polymer layer comprises polyamide.

20. An electronic device, characterized in that: The invention comprises the secondary battery according to any one of claims 1 to 19.

21. A method for manufacturing a secondary battery, for preparing the secondary battery according to any one of claims 1 to 19, characterized in that: include: Providing the packaging film and the electrode assembly, and wrapping the packaging film on the outer surface of the electrode assembly; The glue layer is provided and coated on the surface of the packaging film facing away from the electrode assembly.

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