Secondary battery and electronic device

Abstract

The invention relates to a secondary battery and electronic equipment, the secondary battery comprises a shell and an electrode assembly, and the electrode assembly is accommodated in the shell. The shell comprises a first macromolecule layer, a bonding layer and a metal layer, the two opposite surfaces of the bonding layer are bonded to the first macromolecule layer and the metal layer respectively, the tensile elongation at break of the first macromolecule layer is larger than that of the metal layer, the bonding layer comprises a first mesh area, the first mesh area is provided with a plurality of first holes, and the first holes are communicated with the first mesh area. In the thickness direction of the bonding layer, the first mesh area is located between the first polymer layer and the metal layer. According to the secondary battery and the electronic equipment, the problem of short circuit of the secondary battery can be solved.

Description

Technical Field

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

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

[0003] The inventors of this application have found that when a secondary battery is damaged by external force, the housing is prone to extend to the fracture of the electrode along with the external force, resulting in the contact between the aluminum interlayer of the housing and the electrode and thus causing a short circuit. By providing a mesh area on the housing, the tensile fracture elongation rate of the housing can be reduced, and further the possibility of the aluminum interlayer in the housing being extended by external force and contacting the electrode to cause a short circuit can be reduced.

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

[0005] According to the first aspect of this application, a secondary battery is provided, which includes a housing and an electrode assembly, and the electrode assembly is received in the housing. The housing includes a first polymer layer, an adhesive layer, and a metal layer. The two opposite surfaces of the adhesive layer are respectively adhered to the first polymer layer and the metal layer. The adhesive layer includes a first mesh area, and the first mesh area is provided with a plurality of first holes. Along the thickness direction of the adhesive layer, the first mesh area is located between the first polymer layer and the metal layer.

[0006] In the above technical solution, the housing includes a first polymer layer, an adhesive layer, and a metal layer. The tensile fracture elongation rate of the first polymer layer is greater than that of the metal layer. The first polymer layer and the metal layer are adhered through the adhesive layer. The high tensile fracture elongation rate of the first polymer layer will act on the metal layer. When the secondary battery is damaged by external force, the housing is prone to extend to the fracture of the electrode along with the external force, resulting in the contact between the aluminum interlayer of the housing and the electrode and thus causing a short circuit. By providing a first mesh area on the adhesive layer, the first mesh area is provided with a plurality of first holes. Along the thickness direction of the adhesive layer, the first mesh area is located between the first polymer layer and the metal layer. The possibility that the first polymer layer acts on the metal layer with a high tensile fracture elongation rate at the first mesh area can be reduced. The tensile fracture elongation rate of the housing at the first mesh area can be reduced. When the housing is damaged by external force, it will break in advance. The possibility that the aluminum interlayer of the housing extends to the fracture of the electrode under the action of external force can be reduced. The possibility that the aluminum interlayer of the housing contacts the electrode to cause a short circuit can be reduced.

[0007] In some preferred embodiments, along the thickness direction of the adhesive layer, the projection of the first polymer layer covers the first mesh area, and the projection of the metal layer covers the first mesh area, which can increase the non-bonding area between the first polymer layer and the metal layer, can further reduce the possibility that the first polymer layer acts on the metal layer with a high tensile fracture elongation rate at the first mesh area, and can further reduce the tensile fracture elongation rate of the housing.

[0008] In some preferred embodiments, the electrode assembly is connected with a tab, and the tab extends out of the housing along the first direction. Along the first direction, the housing includes opposite first and second edges. The distance between the first mesh area and the first edge is L1, and the distance between the first mesh area and the second edge is L2, where 0.5 mm ≤ L1 ≤ 5 mm and 0.5 mm ≤ L2 ≤ 5 mm. Since the housing needs to be stamped and the first and second edges of the housing are easily collided and worn, if the tensile fracture elongation rate of the first and second edges is reduced, it is difficult for the housing to meet the stamping requirements, and the first and second edges are easily damaged. By defining L1 ≥ 0.5 mm, the possibility that the first mesh area affects the tensile fracture elongation rate of the first edge can be reduced, which is beneficial for the housing to meet the stamping requirements and can reduce the possibility of damage to the first edge. By defining L1 ≤ 5 mm, it is beneficial to increase the area of the first mesh area, and thus beneficial to further reduce the tensile fracture elongation rate of the housing. By defining L2 ≥ 0.5 mm, the possibility that the first mesh area affects the tensile fracture elongation rate of the second edge can be reduced, which is beneficial for the housing to meet the stamping requirements and can reduce the possibility of damage to the second edge. By defining L2 ≤ 5 mm, it is beneficial to increase the area of the first mesh area, and thus beneficial to further reduce the tensile fracture elongation rate of the housing.

[0009] In some preferred embodiments, along the second direction, the housing includes opposite third and fourth edges. The distance between the first mesh area and the third edge is W1, and the distance between the first mesh area and the fourth edge is W2, where 0.5 mm ≤ W1 ≤ 5 mm and 0.5 mm ≤ W2 ≤ 5 mm. The first direction, the second direction, and the third direction are perpendicular to each other in pairs, and the third direction is the thickness direction of the electrode assembly. By defining W1 ≥ 0.5 mm, the possibility that the first mesh area affects the tensile fracture elongation rate of the third edge can be reduced, and the possibility of damage to the third edge can be reduced. By defining W1 ≤ 5 mm, it is beneficial to increase the area of the first mesh area, and thus beneficial to further reduce the tensile fracture elongation rate of the housing. By defining W2 ≥ 0.5 mm, the possibility that the first mesh area affects the tensile fracture elongation rate of the fourth edge can be reduced, and the possibility of damage to the fourth edge can be reduced. By defining W2 ≤ 5 mm, it is beneficial to increase the area of the first mesh area, and thus beneficial to further reduce the tensile fracture elongation rate of the housing.

[0010] In some preferred embodiments, the maximum value among L1 and L2 is L3, and |L1 - L2| ≤ 10% L3. This can make the first mesh region located in the middle region of the housing in the first direction, and can reduce the possibility of the first mesh region approaching the first edge and the second edge. Among them, due to processing errors, the difference between L1 and L2 within a certain range can also meet the requirements.

[0011] In some preferred embodiments, the maximum value among W1 and W2 is W3, and |W1 - W2| ≤ 10% W3. This can make the first mesh region located in the middle region of the housing in the second direction, and can reduce the possibility of the first mesh region approaching the third edge and the fourth edge. Among them, due to processing errors, the difference between W1 and W2 within a certain range can also meet the requirements.

[0012] In some preferred embodiments, along the thickness direction of the adhesive layer, the first hole is located between the first polymer layer and the metal layer, which can reduce the possibility of the first polymer layer applying the high tensile fracture elongation rate to the metal layer at the first hole, and can reduce the tensile fracture elongation rate of the housing at the first hole. The area of the first mesh region is S1, and the sum of the areas of all the first holes is S2. The ratio of S2 to S1 is 50% to 90%. By setting the ratio of S2 to S1 ≥ 50%, the possibility of the first polymer layer applying the high tensile fracture elongation rate to the metal layer at the first mesh region can be further reduced, and the tensile fracture elongation rate of the housing at the first mesh region can be further reduced. However, the larger the ratio of S2 to S1, the lower the tensile fracture elongation rate of the housing at the first mesh region, and the easier the housing is to be damaged. By setting the ratio of S2 to S1 ≤ 90%, it is beneficial to reduce the possibility of the housing being damaged due to the lower tensile fracture elongation rate at the first mesh region.

[0013] In some preferred embodiments, the first hole is a rectangular hole, which is beneficial to improving the convenience of production. Among them, the first hole can also be circular or any irregular shape, and can be adjusted according to the production method, which is beneficial to meeting different production methods.

[0014] In some preferred embodiments, the width of the first hole is 3 mm to 10 mm. The larger the width of the first hole, the smaller the tensile fracture elongation rate of the housing at the first mesh region. Therefore, by setting the width of the first hole ≥ 3 mm, it is beneficial to further reduce the tensile fracture elongation rate of the housing at the first mesh region. However, the smaller the tensile fracture elongation rate of the housing, the greater the possibility of the housing being damaged, and the housing needs a certain tensile fracture elongation rate under the daily use conditions. If the tensile fracture elongation rate is too low, it cannot meet the requirements. By setting the width of the first hole ≤ 10 mm, it is beneficial to reduce the possibility of the housing being damaged at the first mesh region, and is beneficial to ensuring the tensile fracture elongation rate of the housing under the daily use conditions.

[0015] In some preferred embodiments, the length of the first hole is the same as the width of the first mesh region. The greater the length of the first hole, the smaller the tensile fracture elongation rate of the housing in the first mesh region. By setting the length of the first hole to be the same as the width of the first mesh region, it is beneficial to further reduce the tensile fracture elongation rate of the housing in the first mesh region. It can be understood that due to processing errors, the length of the first hole being the same as the width of the first mesh region means that the length of the first hole is approximately the same as the width of the first mesh region, and a difference between the length of the first hole and the width of the first mesh region can also meet the requirements.

[0016] In some preferred embodiments, in the length direction of the first mesh region, the edge of the first hole close to the edge of the first mesh region coincides with the edge of the first mesh region, which is beneficial to increasing the area ratio of the first hole in the first mesh region and is beneficial to reducing the tensile fracture elongation rate of the housing in the first mesh region. It can be understood that due to processing errors, the coincidence of the edge of the first hole and the edge of the first mesh region means that the edge of the first hole approximately coincides with the edge of the first mesh region, and a distance between the edge of the first hole and the edge of the first mesh region can also meet the requirements.

[0017] In some preferred embodiments, the first holes are uniformly distributed in the first mesh region, which is beneficial to improving the uniformity of the tensile fracture elongation rate of the housing in the first mesh region. It can be understood that the uniform distribution of the first holes in the first mesh region means that the first holes are approximately uniformly distributed in the first mesh region, and due to processing errors, the first holes may not be completely uniformly distributed.

[0018] In some preferred embodiments, along the third direction, the housing includes a first wall, and the first mesh region is located on the first wall. The third direction is the thickness direction of the electrode assembly. Since the first wall of the electrode assembly in the thickness direction is more likely to come into contact with the pole piece and cause a short circuit, by providing the first mesh region on the first wall, the possibility that the aluminum interlayer of the first wall extends to the pole piece fracture under the action of external force can be reduced, the possibility that the aluminum interlayer of the first wall contacts the pole piece and causes a short circuit can be reduced, and the possibility that the housing and the pole piece short-circuit can be further reduced.

[0019] In some preferred embodiments, the housing includes a second wall opposite to the first wall along the third direction. The adhesive layer includes a second mesh region, and the second mesh region is located on the second wall, which can reduce the possibility that the aluminum interlayer of the second wall extends to the pole piece fracture under the action of external force and can reduce the possibility that the aluminum interlayer of the second wall contacts the pole piece and causes a short circuit. Along the thickness direction of the adhesive layer, the second mesh region is located between the first polymer layer and the metal layer, which can reduce the possibility that the first polymer layer acts on the metal layer with a high tensile fracture elongation rate at the second mesh region and can reduce the tensile fracture elongation rate of the housing in the second mesh region.

[0020] In some preferred embodiments, the first polymer layer comprises polyamide to enhance the strength and tensile elongation at break of the housing.

[0021] In some preferred embodiments, the adhesive layer comprises polyurethane to enhance the adhesive property of the adhesive layer.

[0022] In some preferred embodiments, the metal layer comprises aluminum to enhance the plasticity of the housing.

[0023] In some preferred embodiments, the housing further comprises a second polymer layer disposed on the surface of the metal layer facing away from the adhesive layer, and the second polymer layer comprises polypropylene to facilitate the encapsulation of the housing.

[0024] In a second aspect, the present application also provides an electronic device comprising a secondary battery according to any one of the embodiments of the first aspect described above.

[0025] Additional aspects and advantages of the embodiments of the present application will be described, shown, or elucidated in part in the subsequent description, or by the implementation of the embodiments of the present application. Description of the Drawings

[0026] One or more embodiments are illustrated by corresponding drawings. These illustrative descriptions do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings are represented as similar elements, unless otherwise stated, and the dimensions in the drawings do not constitute a proportional limitation.

[0027] Figure 1 It is a schematic structural diagram of a secondary battery according to some embodiments of the present application;

[0028] Figure 2 It is a schematic structural diagram of an electrode assembly according to some embodiments of the present application;

[0029] Figure 3 It is a schematic structural diagram of a secondary battery according to some embodiments of the present application;

[0030] Figure 4 It is a schematic structural diagram of a housing according to some embodiments of the present application;

[0031] Figure 5 It is a schematic structural diagram of a secondary battery according to some embodiments of the present application;

[0032] Figure 6 It is a schematic structural diagram of a secondary battery according to some embodiments of the present application;

[0033] Figure 7 It is a schematic structural diagram of a secondary battery according to some embodiments of the present application.

[0034] Description of the Reference Numerals:

[0035] 100. Secondary battery;

[0036] 10. Housing;

[0037] 11. First polymer layer; 12. Adhesive layer; 121. First mesh region; 1211. First hole; 122. Second mesh region; 1221. Second hole; 13. Metal layer; 14. Second polymer layer;

[0038] 151. First edge; 152. Second edge; 153. Third edge; 154. Fourth edge;

[0039] 161. First wall; 162. Second wall;

[0040] 20. Electrode assembly; 20a. Tab; 21. Positive electrode plate; 22. Negative electrode plate; 23. Separator;

[0041] X. First direction; Y. Second direction; Z. Third direction. Detailed implementation manners

[0042] 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.

[0043] In the present application, referring to "embodiment" means that the specific features, structures or characteristics described in connection with the embodiment may 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.

[0044] 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 two or more, unless otherwise clearly and specifically defined.

[0045] 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 three relationships may exist. For example, A and / or B may 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.

[0046] 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 description, 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 absolute 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 as "straight lines" or "planes".

[0047] The first direction X, the second direction Y, and the third direction Z of the present application are two-way directions, that is, the first direction X includes the direction indicated by the arrow in the drawing and its opposite direction, the second direction Y includes the direction indicated by the arrow in the drawing and its opposite direction, and the third direction Z includes the direction indicated by the arrow in the drawing and its opposite direction.

[0048] The technical features involved in different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0049] 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 marked in the figure), and 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 first direction X (the length direction of the electrode assembly 20) to assist the electrode assembly 20 in performing energy transfer with an external electronic device.

[0050] Regarding the above electrode assembly 20, please refer to Figure 2 Figure 2 shows the laminated 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. The positive electrode sheet 21 and the negative electrode sheet 22 are alternately laminated, 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 laminated structure as an example for description, in some other embodiments, the electrode assembly 20 can also be a wound structure or other structures. For example, after the positive electrode sheet 21, the separator 23, and the negative electrode sheet 22 are laminated in sequence, they are then wound to form a wound electrode assembly 20.

[0051] In some embodiments, please refer to Figure 3 and Figure 4, the housing 10 includes a first polymer layer 11, an adhesive layer 12, and a metal layer 13. The two opposite surfaces of the adhesive layer 12 are respectively adhered to the first polymer layer 11 and the metal layer 13. The tensile fracture elongation rate of the first polymer layer 11 is greater than that of the metal layer 13. The high tensile fracture elongation rate of the first polymer layer will act on the metal layer. When the secondary battery 100 is damaged by an external force, the housing 10 is likely to extend along with the external force to the fracture of the electrode tab, resulting in the aluminum interlayer of the housing 10 coming into contact with the electrode tab and thus causing a short circuit.

[0052] To improve the above problems, in the embodiments of the present application, the adhesive layer 12 includes a first mesh region 121. The first mesh region 121 is provided with a plurality of first holes 1211. Along the thickness direction of the adhesive layer 12, the first mesh region 121 is located between the first polymer layer 11 and the metal layer 13. By providing the first mesh region 121 in the adhesive layer 12, and the first mesh region 121 is provided with a plurality of first holes 1211, and along the thickness direction of the adhesive layer 12, the first mesh region 121 is located between the first polymer layer 11 and the metal layer 13, the possibility that the first polymer layer 11 acts on the metal layer 13 with a high tensile fracture elongation rate at the first mesh region 121 can be reduced, the tensile fracture elongation rate of the housing 10 at the first mesh region 121 can be reduced, the housing 10 will fracture in advance when it is damaged by an external force, the possibility that the aluminum interlayer of the housing 10 extends along with the external force to the fracture of the electrode tab can be reduced, and the possibility that the aluminum interlayer of the housing 10 comes into contact with the electrode tab and causes a short circuit can be reduced.

[0053] In some embodiments, along the thickness direction of the adhesive layer 12, the projection of the first polymer layer 11 covers the first mesh region 121, and the projection of the metal layer 13 covers the first mesh region 121. The non - adhered area between the first polymer layer 11 and the metal layer 13 can be increased, the possibility that the first polymer layer 11 acts on the metal layer 13 with a high tensile fracture elongation rate at the first mesh region 121 can be further reduced, and the tensile fracture elongation rate of the housing 10 can be further reduced.

[0054] In some embodiments, the first polymer layer 11 includes polyamide to enhance the strength and tensile fracture elongation rate of the housing 10, which is beneficial to meeting the stamping requirements of the housing 10.

[0055] In some embodiments, the adhesive layer 12 includes polyurethane to enhance the adhesion performance of the adhesive layer 12.

[0056] In some embodiments, the metal layer 13 includes aluminum to enhance the plasticity of the housing 10.

[0057] In some embodiments, the housing 10 further includes a second polymer layer 14. The second polymer layer 14 is disposed on the surface of the metal layer 13 facing away from the adhesive layer 12. The second polymer layer 14 includes polypropylene to make the housing 10 easy to encapsulate.

[0058] In some embodiments, referring to Figure 3 , along the first direction X, the housing 10 includes opposite first and second edges 151 and 152. The distance between the first mesh region 121 and the first edge 151 is L1, and the distance between the first mesh region 121 and the second edge 152 is L2, where 0.5 mm ≤ L1 ≤ 5 mm and 0.5 mm ≤ L2 ≤ 5 mm. Since the housing 10 needs to be stamped and the first and second edges 151 and 152 of the housing 10 are prone to being collided and worn, if the elongation at break of the first and second edges 151 and 152 is reduced, it is difficult for the housing 10 to meet the stamping requirements, and the first and second edges 151 and 152 are prone to breakage. By defining L1 ≥ 0.5 mm, the possibility that the first mesh region 121 affects the elongation at break of the first edge 151 can be reduced, and the possibility of breakage of the first edge 151 can be reduced. By defining L1 ≤ 5 mm, it is beneficial to increase the area of the first mesh region 121, which in turn is beneficial to further reducing the elongation at break of the housing 10. By defining L2 ≥ 0.5 mm, the possibility that the first mesh region 121 affects the elongation at break of the second edge 152 can be reduced, which is beneficial for the housing 10 to meet the stamping requirements, and the possibility of breakage of the second edge 152 can be reduced. By defining L2 ≤ 5 mm, it is beneficial to increase the area of the first mesh region 121, which in turn is beneficial to further reducing the elongation at break of the housing 10.

[0059] In some embodiments, along the second direction Y (the width direction of the electrode assembly 20), the housing 10 includes opposite third and fourth edges 153 and 154. The distance between the first mesh region 121 and the third edge 153 is W1, and the distance between the first mesh region 121 and the fourth edge 154 is W2, where 0.5 mm ≤ W1 ≤ 5 mm and 0.5 mm ≤ W2 ≤ 5 mm. The first direction X, the second direction Y, and the third direction Z are perpendicular to each other in pairs, and the third direction Z is the thickness direction of the electrode assembly 20. By defining W1 ≥ 0.5 mm, the possibility that the first mesh region 121 affects the elongation at break of the third edge 153 can be reduced, and the possibility of breakage of the third edge 153 can be reduced. By defining W1 ≤ 5 mm, it is beneficial to increase the area of the first mesh region 121, which in turn is beneficial to further reducing the elongation at break of the housing 10. By defining W2 ≥ 0.5 mm, the possibility that the first mesh region 121 affects the elongation at break of the fourth edge 154 can be reduced, and the possibility of breakage of the fourth edge 154 can be reduced. By defining W2 ≤ 5 mm, it is beneficial to increase the area of the first mesh region 121, which in turn is beneficial to further reducing the elongation at break of the housing 10.

[0060] In some embodiments, L1 = L2, which can make the first mesh area 121 located in the middle area of the housing 10 in the first direction X, and can reduce the possibility that the first mesh area 121 is close to the first edge 151 and the second edge 152. Among them, due to machining errors, L1 = L2 means |L1 - L2| ≤ 10%L1 or |L1 - L2| ≤ 10%L2. In some embodiments, the largest value among L1 and L2 is L3, |L1 - L2| ≤ 10%L3, and the difference between L1 and L2 within a certain range can also meet the requirements, which is beneficial to improving the convenience of machining.

[0061] In some embodiments, W1 = W2, which can make the first mesh area 121 located in the middle area of the housing 10 in the second direction Y, and can reduce the possibility that the first mesh area 121 is close to the third edge 153 and the fourth edge 154. Among them, due to machining errors, W1 = W2 means |W1 - W2| ≤ 10%W1 or |W1 - W2| ≤ 10%W2. In some embodiments, the largest value among W1 and W2 is W3, |W1 - W2| ≤ 10%W3, and the difference between W1 and W2 within a certain range can also meet the requirements, which is beneficial to improving the convenience of machining.

[0062] In some embodiments, please refer to Figure 4 and Figure 5 , along the thickness direction of the adhesive layer 12, the first hole 1211 is located between the first polymer layer 11 and the metal layer 13, which can reduce the possibility that the first polymer layer 11 at the first hole 1211 applies the high tensile fracture elongation rate to the metal layer 13, and can reduce the tensile fracture elongation rate of the housing 10 at the first hole 1211. The area of the first mesh area 121 is S1, and the sum of the areas of all the first holes 1211 is S2. The ratio of S2 to S1 is 50% to 90%. By setting the ratio of S2 to S1 ≥ 50%, the possibility that the first polymer layer 11 at the first mesh area 121 applies the high tensile fracture elongation rate to the metal layer 13 can be further reduced, and the tensile fracture elongation rate of the housing 10 at the first mesh area 121 can be further reduced. However, the larger the ratio of S2 to S1, the lower the tensile fracture elongation rate of the housing 10 at the first mesh area 121, and the easier the housing 10 is to be damaged. By setting the ratio of S2 to S1 ≤ 90%, it is beneficial to reduce the possibility that the housing 10 is damaged due to the lower tensile fracture elongation rate at the first mesh area 121.

[0063] In some embodiments, the first hole 1211 is a rectangular hole, which is beneficial to improving the convenience of production. In some other embodiments, the shape of the first hole 1211 can be circular, triangular, fan-shaped, polygonal, and any irregular shape, which can meet different processing requirements.

[0064] In some embodiments, the width of the first hole 1211 is 3 mm to 10 mm. The larger the width of the first hole 1211 is, the smaller the tensile fracture elongation rate of the housing 10 in the first mesh region 121 will be. Therefore, by setting the width of the first hole 1211 ≥ 3 mm, it is beneficial to further reduce the tensile fracture elongation rate of the housing 10 in the first mesh region 121. However, the smaller the tensile fracture elongation rate of the housing 10 is, the greater the possibility of damage to the housing 10 will be, and the housing 10 requires a certain tensile fracture elongation rate under normal use conditions. A lower tensile fracture elongation rate cannot meet the requirements. By setting the width of the first hole 1211 ≤ 10 mm, it is beneficial to reduce the possibility of damage to the housing 10 in the first mesh region 121, and it is beneficial to ensure the tensile fracture elongation rate of the housing 10 under normal use conditions.

[0065] In some embodiments, the length of the first hole 1211 is the same as the width of the first mesh region 121. The larger the length of the first hole 1211 is, the smaller the tensile fracture elongation rate of the housing 10 in the first mesh region 121 will be. By setting the length of the first hole 1211 to be the same as the width of the first mesh region 121, it is beneficial to further reduce the tensile fracture elongation rate of the housing 10 in the first mesh region 121. It can be understood that due to processing errors, the length of the first hole 1211 being the same as the width of the first mesh region 121 means that the length of the first hole 1211 is approximately the same as the width of the first mesh region 121, and a difference between the length of the first hole 1211 and the width of the first mesh region 121 can also meet the requirements.

[0066] In some embodiments, in the length direction of the first mesh region 121, the edge of the first hole 1211 close to the edge of the first mesh region 121 coincides with the edge of the first mesh region 121, which is beneficial to increasing the area ratio of the first hole 1211 in the first mesh region 121 and beneficial to reducing the tensile fracture elongation rate of the housing 10 in the first mesh region 121. It can be understood that due to processing errors, the edge of the first hole 1211 coinciding with the edge of the first mesh region 121 means that the edge of the first hole 1211 approximately coincides with the edge of the first mesh region 121, and a distance between the edge of the first hole 1211 and the edge of the first mesh region 121 can also meet the requirements.

[0067] In some embodiments, the first holes 1211 are evenly distributed in the first mesh region 121, which is beneficial to improving the uniformity of the tensile fracture elongation rate of the housing 10 in the first mesh region 121. It can be understood that the first holes 1211 being evenly distributed in the first mesh region 121 means that the first holes 1211 are approximately evenly distributed in the first mesh region 121. Due to processing errors, the first holes 1211 may not be completely evenly distributed.

[0068] In some embodiments, the distance between two adjacent first holes 1211 is 3 mm to 7 mm. The smaller the distance between two adjacent first holes 1211, the smaller the tensile fracture elongation rate of the housing 10 in the first mesh region 121. Therefore, by setting the distance between two adjacent first holes 1211 ≤ 7 mm, it is beneficial to further reduce the tensile fracture elongation rate of the housing 10 in the first mesh region 121. However, the smaller the tensile fracture elongation rate of the housing 10, the greater the possibility of damage to the housing 10. Therefore, by setting the distance between two adjacent first holes 1211 ≥ 3 mm, it is beneficial to reduce the possibility of damage to the housing 10 in the first mesh region 121.

[0069] In some embodiments, along the third direction Z (the thickness direction of the electrode assembly 20), please refer to Figure 5 and Figure 6 , the housing 10 includes a first wall 161, and the first mesh region 121 is located on the first wall 161. Since the first wall 161 of the electrode assembly 20 in the thickness direction is more likely to come into contact with the pole piece and cause a short circuit, by providing the first mesh region 121 on the first wall 161, the possibility that the aluminum interlayer of the first wall 161 extends to the pole piece fracture under the action of external force can be reduced, the possibility that the aluminum interlayer of the first wall 161 comes into contact with the pole piece and causes a short circuit can be reduced, and the possibility that the housing 10 and the pole piece are short-circuited can be further reduced.

[0070] In some embodiments, please refer to Figure 6 and Figure 7 , the housing 10 includes a second wall 162 disposed opposite to the first wall 161 along the third direction Z. The adhesive layer 12 includes a second mesh region 122, and the second mesh region 122 is located on the second wall 162, which can reduce the possibility that the aluminum interlayer of the second wall 162 extends to the pole piece fracture under the action of external force, and can reduce the possibility that the aluminum interlayer of the second wall 162 comes into contact with the pole piece and causes a short circuit. Along the thickness direction of the adhesive layer 12, the second mesh region 122 is located between the first polymer layer 11 and the metal layer 13, which can reduce the possibility that the first polymer layer 11 acts on the metal layer 13 with a high tensile fracture elongation rate at the second mesh region 122, and can reduce the tensile fracture elongation rate of the housing 10 in the second mesh region 122.

[0071] In some embodiments, the second mesh region 122 is provided with second holes 1221. Along the thickness direction of the adhesive layer 12, the second holes 1221 are located between the first polymer layer 11 and the metal layer 13, which can reduce the possibility that the first polymer layer 11 acts on the metal layer 13 with a high tensile fracture elongation rate at the second holes 1221, and can reduce the tensile fracture elongation rate of the housing 10 at the second holes 1221.

[0072] In some embodiments, the second hole 1221 is a rectangular hole, which is beneficial to improving the convenience of production. In some other embodiments, the shape of the second hole 1221 can be circular, triangular, fan-shaped, polygonal, and any irregular shape, which can meet different processing requirements.

[0073] In some embodiments, the structure, size, and area of the second mesh hole region 122 can be the same as those of the first mesh hole region 121, and the shape, size, area, and number of the second holes 1221 can be the same as those of the first holes 1211, which is beneficial to improving the convenience of production.

[0074] In a second aspect of the present application, an electronic device is further proposed, including the secondary battery 100 according to any one of the embodiments in the first aspect above. The electronic device in the embodiments of the present application is not particularly limited, and it can be any electronic device known in the prior art. For example, the electronic device includes but is not limited to Bluetooth headsets, mobile phones, tablets, laptop computers, electric toys, electric tools, battery cars, electric vehicles, ships, spacecraft, and the like. Among them, the electric toys can include fixed or mobile electric toys, such as game consoles, electric vehicle toys, electric ship toys, and electric aircraft toys, etc., and the spacecraft can include airplanes, rockets, space shuttles, and spaceships, etc.

[0075] Test part:

[0076] 1. Tensile test:

[0077] The housing is made into a test sample with a length of 100 mm and a width of 15 mm using a special tensile cutting knife, and the test sample is fixed to the test fixture of a high-speed tensile machine. The tensile speed is 50 ± 0.5 mm / min, and the tensile spacing is 50 mm. When the sample is broken, record the maximum tensile force and the sample length. The maximum tensile force is the breaking tensile force. The tensile fracture elongation rate = (the length of the sample at break - the initial sample length) / the initial sample length.

[0078] 2. Nail test:

[0079] The sample secondary battery is first fully charged, placed flat on the test bench, and tested from the center position of the sample at a speed of 150 ± 1.5 mm / s using 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. After the sample is completely pierced, the passing criterion is that the battery core does not catch fire or explode after the test is completed.

[0080] Example 1

[0081] <Preparation of the positive electrode sheet>:

[0082] Use aluminum foil as the positive current collector, and evenly 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.

[0083] <Preparation of the negative electrode sheet>:

[0084] Use copper foil as the negative current collector, and evenly 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.

[0085] <Preparation of the electrolyte>:

[0086] Use a solution prepared by mixing lithium salt LiPF₆ and 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.

[0087] <Preparation of the housing>:

[0088] Use a polypropylene layer as the second polymer layer and aluminum foil as the metal layer. Stack the second polymer layer and the metal layer, and coat polyurethane on the surface of the metal layer facing away from the second polymer layer to form an adhesive layer. The adhesive layer includes a first mesh area. The area S1 of the first mesh area is 4000 mm 2 (80 mm long and 50 mm wide). The first mesh area includes a rectangular first hole where the polyurethane layer is not coated. The width of the first hole in the first direction is 5 mm, the distance between adjacent two first holes in the first direction is 5 mm, the length of the first hole in the second direction is 50 mm, and the sum of the areas of all the first holes in the first hollow area is S2. The ratio of S2 to S1 is 50%. Use a polyamide layer as the first polymer layer, and stack the first polymer layer on the surface of the adhesive layer facing away from the metal layer to obtain the housing. The total thickness of the housing is 103 μm.

[0089] <Preparation of the secondary battery>:

[0090] Weld the tabs of the positive electrode sheet and the negative electrode sheet, and then wind the positive electrode sheet and the negative electrode sheet. The positive electrode sheet and the negative electrode sheet are separated by a polyethylene separator to prepare the electrode assembly.

[0091] Wrap the housing around the outer surface of the electrode assembly (the second polymer layer is closer to the electrode assembly than the first polymer layer). After top-side sealing, inkjet coding, vacuum drying, electrolyte injection, and high-temperature standing, formation and capacity measurement are carried out to obtain a secondary battery. The housing includes a first edge and a second edge opposite to each other in a first direction. The distance between the first mesh region and the first edge is 5 mm, and the distance between the first mesh region and the second edge is 5 mm. The housing includes a third edge and a fourth edge opposite to each other in a second direction. The distance between the first mesh region and the third edge is 5 mm, and the distance between the first mesh region and the fourth edge is 5 mm. The length of the housing in the first direction is 90 mm, and the width of the housing in the second direction is 60 mm.

[0092] The relevant parameters in Comparative Example 1 and Examples 1 to 8 are shown in Table 1 below.

[0093] Among them, the first mesh region is not provided in the adhesive layer of the housing in Comparative Example 1. The sum of the areas S2 of all the first holes in the first mesh region is different in Examples 1 to 4, and the widths of the first holes in the first mesh region are different in Examples 1 and 5 to 8.

[0094] Table 1

[0095]

[0096] Note: In Table 1, "\ " means that the parameter is not included.

[0097] According to Table 1 above, in combination with Comparative Example 1 and Examples 1 to 8, it can be seen that by providing the first mesh region in the adhesive layer, the first mesh region is provided with first holes, and the first mesh region is located between the first polymer layer and the metal layer in the thickness direction of the adhesive layer, the possibility that the first polymer layer at the first mesh region acts on the metal layer with a high tensile fracture elongation rate can be reduced, the tensile fracture elongation rate of the housing at the first mesh region can be reduced, the housing will break in advance when subjected to external force damage, the possibility that the aluminum sandwich layer of the housing extends to the pole piece fracture under the action of external force can be reduced, and the possibility that the aluminum sandwich layer of the housing contacts and shorts with the pole piece can be reduced. Therefore, the nail penetration pass rate of the secondary battery can be improved.

[0098] Combined with Embodiments 1 to 4, it can be seen that the area of the first mesh region is S1, and the sum of the areas of all the first holes is S2. The ratio of S2 to S1 ≥ 50%, which can further reduce the possibility that the first polymer layer at the first mesh region applies a high tensile fracture elongation rate to the metal layer, can further reduce the tensile fracture elongation rate of the housing at the first mesh region. Therefore, the needle penetration rate of the secondary battery can be further improved. When the ratio of S2 to S1 is less than 50%, the tensile fracture elongation rate of the housing at the first mesh region will increase. When the ratio of S2 to S1 is greater than 90%, the needle penetration rate is not further improved, the tensile fracture elongation rate of the housing at the first mesh region will be lower, and the housing is prone to breakage.

[0099] Combined with Embodiments 5 to 8, it can be seen that the width of the first hole is 3 mm to 10 mm, and the secondary battery has a good needle penetration rate. The larger the width of the first hole, the smaller the tensile fracture elongation rate of the housing at the first mesh region, and the higher the needle penetration rate of the secondary battery. Therefore, by setting the width of the first hole ≥ 3 mm, it is beneficial to further reduce the tensile fracture elongation rate of the housing at the first mesh region, and thus further improve the needle penetration rate of the secondary battery. However, the smaller the tensile fracture elongation rate of the housing, the greater the possibility of housing breakage. Therefore, by setting the width of the first hole ≤ 10 mm, it is beneficial to reduce the possibility of housing breakage due to a relatively small tensile fracture elongation rate of the housing at the first mesh region. If the width of the first hole is greater than 10 mm, the tensile fracture elongation rate of the housing at the first mesh region will be smaller, and the housing is prone to breakage.

[0100] The above are only the 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 to other related technical fields, shall be included in the patent protection scope of the present application by the same token.

Claims

1. A secondary battery, comprising a housing and an electrode assembly, wherein the electrode assembly is accommodated in the housing; It is characterized in that The shell includes a first polymer layer, an adhesive layer and a metal layer. The opposite surfaces of the adhesive layer are respectively bonded to the first polymer layer and the metal layer. The adhesive layer includes a first mesh area. The first mesh area is provided with a plurality of first holes. Along the thickness direction of the adhesive layer, the first mesh area is located between the first polymer layer and the metal layer.

2. The secondary battery according to claim 1, characterized in that: Along the thickness direction of the adhesive layer, the projection of the first polymer layer covers the first mesh area, and the projection of the metal layer covers the first mesh area.

3. The secondary battery according to claim 1, characterized in that: The electrode assembly is connected to a pole ear, which extends out of the shell along a first direction. Along the first direction, the shell includes a first edge and a second edge relative to each other. The distance between the first mesh area and the first edge is L1, and the distance between the first mesh area and the second edge is L2, 0.5mm≤L1≤5mm, 0.5mm≤L2≤5mm.

4. The secondary battery according to claim 3, characterized in that: Along the second direction, the shell includes a third edge and a fourth edge relative to each other, the distance between the first mesh area and the third edge is W1, the distance between the first mesh area and the fourth edge is W2, 0.5mm≤W1≤5mm, 0.5mm≤W2≤5mm, the first direction, the second direction and the third direction are perpendicular to each other, and the third direction is the thickness direction of the electrode assembly.

5. The secondary battery according to claim 4, characterized in that: The largest value between L1 and L2 is L3, |L1-L2|≤10%L3; and / or the largest value between W1 and W2 is W3, |W1-W2|≤10%W3.

6. The secondary battery according to claim 1, characterized in that: Along the thickness direction of the adhesive layer, the first holes are located between the first polymer layer and the metal layer, the area of ​​the first mesh region is S1, the sum of the areas of all the first holes is S2, and the ratio of S2 to S1 is 50% to 90%.

7. The secondary battery according to claim 6, characterized in that: The first hole is a rectangular hole.

8. The secondary battery according to claim 7, characterized in that: The width of the first hole is 3 mm to 10 mm.

9. The secondary battery according to claim 1, characterized in that: The length of the first hole is the same as the width of the first mesh area; and / or, in the length direction of the first mesh area, the edge of the first hole close to the edge of the first mesh area coincides with the edge of the first mesh area.

10. The secondary battery according to claim 1, characterized in that: The first holes are evenly distributed in the first mesh area.

11. The secondary battery according to claim 1, characterized in that: Along a third direction, the shell includes a first wall, the first mesh area is located on the first wall, and the third direction is a thickness direction of the electrode assembly.

12. The secondary battery according to claim 11, characterized in that: The shell includes a second wall arranged opposite to the first wall along the third direction, and the adhesive layer includes a second mesh area, the second mesh area is located on the second wall, and along the thickness direction of the adhesive layer, the second mesh area is located between the first polymer layer and the metal layer.

13. The secondary battery according to any one of claims 1 to 12, characterized in that: The first polymer layer includes polyamide; and / or the adhesive layer includes polyurethane; and / or the metal layer includes aluminum.

14. The secondary battery according to any one of claims 1 to 12, characterized in that: The shell further includes a second polymer layer, which is disposed on a surface of the metal layer away from the adhesive layer, and includes polypropylene.

15. An electronic device, characterized in that: The invention comprises the secondary battery according to any one of claims 1 to 14.

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