Secondary battery and electronic device
By bonding and fixing the electrode ears with the current collector in the secondary battery, the short circuit problem caused by welding burrs is solved, higher energy density and production efficiency are achieved, and cost is reduced.
Patent Information
- Application Number
- CN202411985352.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-31
- Publication Date
- 2025-04-08
AI Technical Summary
The welding of the electrode ear and the current collector in the secondary battery is prone to welding burrs, resulting in short-circuit failure.
By bonding and fixing the first pole ear to the first empty foil area with the first seal, the occurrence of welding burrs is avoided, and the bonding and sealing steps are combined into one during the production process, thereby reducing the production process.
It effectively reduces the risk of short circuits in secondary batteries, improves the energy density and production efficiency of batteries, and reduces costs.
Smart Images
Figure CN119786696A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the field of battery technology, and in particular to a secondary battery and an electronic device. Background Art
[0002] The tab serves as a bridge for electrically connecting the secondary battery to the external circuit. It is usually made of metal material. The tab is welded to the current collector inside the secondary battery, which allows the tab to be conductive with the electrode assembly inside the secondary battery, thereby achieving the purpose of transmitting current.
[0003] In order to facilitate the welding of the tabs, double-sided empty foil areas are usually required on the current collector. The welding seat supports the current collector on one side of the empty foil area, and the welding head welds the tabs and the current collector on the other side of the empty foil area. However, the welding of the tabs and the empty foil area of the current collector usually produces some welding burrs, which can easily pierce the isolation film and cause the positive and negative electrodes inside the secondary battery to short-circuit and fail. Summary of the invention
[0004] The purpose of the present application is to provide a secondary battery and an electronic device, aiming to reduce the technical problem that the secondary battery is prone to short circuit.
[0005] According to the first aspect of the present application, a secondary battery is provided, comprising a shell, an electrode assembly and a first pole ear, the shell is provided with an edge seal, and the electrode assembly is provided in the shell; the electrode assembly comprises a first pole piece, the first pole piece comprises a first current collector and a first active material layer superimposed on the surface of the first current collector, the first current collector is provided with a first empty foil area, one end of the first pole ear is connected to the first empty foil area, and the other end extends out of the shell from the edge seal, and a first seal is provided between the first pole ear and the edge seal. The first pole ear comprises a first surface facing the first empty foil area, the first seal comprises a first portion provided on the first surface, the first portion extends between the first pole ear and the first empty foil area, and the first pole ear and the first empty foil area are bonded through the first portion.
[0006] In the above technical solution, the first pole ear is bonded and fixed to the first empty foil area by the first sealant, and there is no welding burr, which can reduce the short circuit of the secondary battery, and there is no need to set a protective rubber layer on the first pole ear or the first empty foil area to cover the burr, which saves the space occupied by the protective rubber layer, and can reduce the cost while improving the energy density of the secondary battery. In addition, the first sealant has good sealing performance, can effectively fill the small gap between the first pole ear and the first empty foil area, and can improve the connection strength between the first pole ear and the first empty foil area. A sealing layer that continuously covers the first pole ear can be formed in the shell, which can not only improve the strength of the first pole ear, reduce the tearing of the first pole ear, but also effectively reduce the bending and skewing of the first pole ear, thereby reducing the risk of short circuit between the first pole ear and other components.
[0007] In addition, the bonding of the first pole ear and the sealing of the shell can be completed in one step. In the production process of the secondary battery, the bonding and sealing steps can be combined into one by extending the first part of the first seal to bond the first pole ear and the first empty foil area of the first current collector, thereby reducing the production process, improving production efficiency and reducing production costs.
[0008] In some embodiments, the first surface is provided with a plurality of first protrusions, the first protrusions protrude relative to the first surface, and the first portion is partially embedded between two adjacent first protrusions. The bonding area between the first pole ear and the first seal can be increased, thereby improving the connection strength between the first pole ear and the first current collector. At the same time, the provision of the first protrusions can not only improve the strength of the first pole ear, but also make the first pole ear have a stronger current carrying capacity, which can reduce the heat generation of the first pole ear while reducing the damage and tearing of the first pole ear.
[0009] In some embodiments, at least a portion of the first protrusion is in contact with the first empty foil area, which can provide a more direct conductive path. Compared with conducting current only by adding conductive particles, direct contact can significantly reduce the contact resistance between the first electrode and the first current collector, which is beneficial to improving the charge and discharge efficiency of the secondary battery.
[0010] In some embodiments, along the first direction, the width of the first protrusion in the second direction is reduced. The first direction is the direction from the first pole ear to the first current collector, and the second direction is the length or width direction of the first pole piece. This can make the first protrusion encounter less resistance in the process of penetrating the first seal, and can more easily penetrate the relatively soft first seal, reducing excessive extrusion or damage to the first seal during the penetration process. In addition, after the first protrusion penetrates, it is beneficial for the first seal to restore its shape around the first protrusion, which is beneficial to filling the gap between the two adjacent first protrusions and improving the connection strength between the first pole ear and the first current collector.
[0011] In some embodiments, at least a portion of the first protrusion is inserted into the first current collector, so that an anchor point can be formed between the first pole ear and the first current collector, providing a more secure mechanical interlocking, and effectively reducing the separation of the first pole ear from the first current collector when the secondary battery is subjected to vibration, impact, etc.
[0012] In some embodiments, along the thickness direction of the first pole piece, at least a portion of the first protrusion penetrates the first current collector, and a more secure interlocking structure can be constructed between the first pole ear and the first current collector, further improving the bonding strength between the first pole ear and the first current collector, and being able to effectively resist strong vibrations, impacts, and extreme acceleration changes, etc., and reduce loosening or detachment between the first pole ear and the first current collector.
[0013] In some embodiments, the first surface is provided with a plurality of first recessed portions, the first recessed portions are recessed relative to the first surface, and the first portion is partially embedded in the first recessed portions. The bonding area between the first pole tab and the first sealant can be increased, thereby improving the connection strength between the first pole tab and the first current collector. At the same time, the first recessed portion can be used as a storage space for the first sealant, so that the first sealant is better retained between the first pole tab and the first current collector.
[0014] In some embodiments, the first pole ear has a second surface facing away from the first empty foil area. The first seal also includes a second portion disposed on the second surface, and along the thickness direction of the first pole piece, within the projection range of the first empty foil area, the second portion covers at least a portion of the first pole ear. The cutting burrs of the first pole ear can be reduced from piercing the isolation membrane, thereby reducing the occurrence of short circuits. At the same time, a double-sided fixed structure of the first pole ear can be formed, reducing the relative displacement between the first pole ear and the first current collector and the shell. It also helps to improve the sealing performance of the secondary battery, further reduce leakage, and reduce the risk of impurities such as external air and moisture entering the interior of the secondary battery.
[0015] In some embodiments, along the width direction of the first pole ear, the first pole ear also includes a third surface and a fourth surface that are relatively arranged, and the third surface and the fourth surface are both connected between the first surface and the second surface. The first seal also includes a third part and a fourth part. Along the thickness direction of the first pole piece, within the projection range of the first empty foil area, the third part is bonded to at least a portion of the third surface, and the fourth part is bonded to at least a portion of the fourth surface. A structure in which the first seal wraps the first pole ear can be formed, and the first seal can be directly sleeved on the first pole ear, and the installation process is simpler. In addition, the first seal wraps the first pole ear to form an all-round fixed structure, which is conducive to dispersing the stress on the first pole ear, thereby reducing problems such as cracks or falling off of the first pole ear due to stress concentration.
[0016] In some embodiments, the first active material layer is provided with a first groove, and the first current collector forms a first empty foil area in the first groove. The first pole piece also includes a second active material layer, and the second active material layer is superimposed on the surface of the first current collector facing away from the first active material layer. Along the thickness direction of the first pole piece, the first groove is located within the projection of the second active material layer. Because the first pole ear and the first current collector are bonded by the first seal, no welding head and welding seat are required, that is, there is no need to open a groove in the second active material layer to place the welding seat, so that the structure of the second active material layer is more complete, and the powder shedding of part of the second active material layer caused by grooving is reduced, so that the second active material layer can be fully utilized, and the energy density of the secondary battery is improved.
[0017] In some embodiments, the secondary battery further includes an isolating membrane and a second pole piece, and an isolating membrane is disposed between the first pole piece and the second pole piece along the thickness direction of the first pole piece. The second active material layer includes a first region, and along the thickness direction of the first pole piece, the projection of the first region coincides with the first groove, and the surface of the first region facing away from the first current collector is at least partially in contact with the isolating membrane. There are no welding burrs, and the first region of the second active material layer not only does not need to be provided with a corresponding groove, but also does not need to be provided with a protective adhesive layer to cover the burrs. Therefore, the first region of the second active material layer can directly contact the isolating membrane, that is, the first region can participate in the electrochemical reaction, thereby improving the energy density of the secondary battery.
[0018] In some embodiments, the secondary battery further includes a separator and a second pole piece. Along the thickness direction of the first pole piece, a separator is provided between the first pole piece and the second pole piece. The first pole piece is a positive pole piece, and the second pole piece is a negative pole piece. The second pole piece includes a second current collector and a third active material layer. The third active material layer is superimposed on the surface of the second current collector facing the first active material layer. The third active material layer includes a second region. Along the thickness direction of the first pole piece, the projection of the second region coincides with the first groove, and the surface of the second region facing the first groove is at least partially in contact with the separator. The second region of the third active material layer does not need to be provided with a protective adhesive layer, so that the second region can participate in the electrochemical reaction normally, thereby improving the energy density of the secondary battery. In addition, because the second pole piece is a negative pole piece, the second pole piece can have sufficient margin to embed the lithium ions released from the first pole piece, which can reduce the occurrence of lithium plating.
[0019] In some embodiments, the secondary battery further includes a second pole tab and a second seal. The second current collector is provided with a second empty foil area, one end of the second pole tab is connected to the second empty foil area, and the other end extends out of the housing from the edge seal, and the second seal is provided between the second pole tab and the edge seal. The second pole tab includes a fifth surface facing the second empty foil area, the second seal includes a fifth portion, the fifth portion extends between the second pole tab and the second empty foil area, and the second pole tab and the second empty foil area are bonded through the fifth portion.
[0020] The second pole ear is bonded and fixed to the second empty foil area by the second sealant, and there is no welding burr, which can reduce the short circuit of the secondary battery. It is not necessary to set a protective adhesive layer on the second pole ear or the second empty foil area to cover the burr, which saves the space occupied by the protective adhesive layer, and can reduce the cost while improving the energy density of the secondary battery. In addition, the second sealant can effectively fill the tiny gap between the second pole ear and the second empty foil area, which can improve the connection strength between the second pole ear and the first empty foil area. A sealing layer that continuously covers the second pole ear can be formed in the shell, which can not only improve the strength of the second pole ear, reduce the tearing of the second pole ear, but also effectively reduce the bending or skewing of the second pole ear, thereby reducing the risk of short circuit between the second pole ear and other components.
[0021] In a second aspect, the present application further proposes an electronic device, comprising a cylindrical battery as in any embodiment of the first aspect described above.
[0022] Additional aspects and advantages of the embodiments of the present application will be described, shown, or explained in part in the subsequent description through implementation of the embodiments of the present application. BRIEF DESCRIPTION OF THE DRAWINGS
[0023] One or more embodiments are exemplarily described by corresponding drawings, which do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings represent similar elements, and unless otherwise stated, the dimensions in the drawings do not constitute proportional limitations.
[0024] Figure 1 A schematic diagram of the structure of a secondary battery in some embodiments of the present application;
[0025] Figure 2 A schematic diagram of the structure of a secondary battery in some embodiments of the present application;
[0026] Figure 3 An exploded schematic diagram of a secondary battery according to some embodiments of the present application;
[0027] Figure 4 A schematic diagram of the stacked structure of an electrode assembly according to some embodiments of the present application;
[0028] Figure 5 This is a schematic structural diagram of a first pole piece in some embodiments of the present application;
[0029] Figure 6 This is a schematic structural diagram of a first pole piece in some embodiments of the present application;
[0030] Figure 7 This is a schematic structural diagram of a first pole piece in some embodiments of the present application;
[0031] Figure 8 This is a schematic structural diagram of a first pole piece in some embodiments of the present application;
[0032] Fig. 9 This is a schematic structural diagram of a first pole piece in some embodiments of the present application;
[0033] Fig.10 This is a schematic structural diagram of a first pole piece in some embodiments of the present application;
[0034] Fig.11 This is a schematic structural diagram of a first pole piece in some embodiments of the present application;
[0035] Fig.12 This is a schematic structural diagram of a first pole piece in some embodiments of the present application;
[0036] Fig.13 This is a schematic structural diagram of a first pole piece in some embodiments of the present application;
[0037] Fig.14 A schematic diagram of a first sealing member wrapping a first electrode tab in some embodiments of the present application;
[0038] Fig.15 This is a schematic diagram of the structure of the second pole piece of some embodiments of the present application.
[0039] Description of reference numerals:
[0040] 100. Secondary battery;
[0041] 10. Shell; 11. Accommodating cavity; 12. Edge sealing; 10a. First bag body; 10b. Second bag body;
[0042] 20. Electrode assembly;
[0043] 21, first pole piece; 211, first current collector; 212, first active material layer; 213, second active material layer; 211a, first empty foil area; 211b, first groove; 2131, first region;
[0044] 22, second pole piece; 221, second current collector; 221a, second empty foil area; 221b, second groove; 222, third active material layer; 2221, second area; 223, fourth active material layer;
[0045] 23. Isolation film;
[0046] 30, first pole ear; 31, first surface; 32, second surface; 33, third surface; 34, fourth surface; 30a, first protrusion; 30b, first depression;
[0047] 40. second pole ear; 41. fifth surface;
[0048] 50. first sealing member; 51. first portion; 52. second portion; 53. third portion; 54. fourth portion;
[0049] 60. second sealing member; 61. fifth portion;
[0050] Z, first direction; X, second direction; Y, third direction. DETAILED DESCRIPTION
[0051] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments.
[0052] Reference to "embodiment" in this application means that a particular feature, structure, or characteristic described in conjunction with the embodiment may be included in at least one embodiment of the present application. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments.
[0053] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.
[0054] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, indicating that there may be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.
[0055] The technical features involved in the different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.
[0056] In the first aspect, the present application proposes a secondary battery 100, please refer to Figure 1 and Figure 2 The secondary battery 100 includes a housing 10, an electrode assembly 20, a first pole tab 30, and a second pole tab 40. The housing 10 can accommodate the electrode assembly 20 and an electrolyte (not shown in the figure). The electrolyte infiltrates the electrode assembly 20 in the housing 10, thereby generating an electrochemical reaction. One end of the first pole tab 30 is connected to the electrode assembly 20 in the housing 10, and the other end of the first pole tab 30 extends out of the housing 10. One end of the second pole tab 40 is connected to the electrode assembly 20 in the housing 10, and the other end of the second pole tab 40 extends out of the housing 10. The first pole tab 30 and the second pole tab 40 have opposite polarities and are used to lead out the positive and negative electrodes of the secondary battery 100.
[0057] For the housing 10, please refer to Figure 1 and Figure 2 The housing 10 encloses a receiving cavity 11, which can accommodate the electrode assembly 20 and the electrolyte (not shown in the figure). In some embodiments, the housing 10 can be formed by punching a layer of metal sheet, and the thickness of the metal sheet can be set to 0.1mm to 0.4mm, so that the housing 10 has a higher punching strength. In some other embodiments, the housing 10 can also be made of soft packaging material, for example, the housing 10 is made of aluminum-plastic film packaging bag, which can make the housing 10 have better plasticity.
[0058] In some embodiments, taking the shell 10 made of a soft package material as an example, please refer to Figure 3 The shell 10 includes a first bag body 10a and a second bag body 10b. The electrode assembly 20 is placed in the first bag body 10a or the second bag body 10b, and the edges of the first bag body 10a and the second bag body 10b are sealed by hot pressing to form a complete shell 10. The edges of the first bag body 10a and the second bag body 10b together form the sealing edge 12 of the shell 10, so that the shell 10 is sealed. The first pole tab 30 and the second pole tab 40 can extend out of the shell 10 from the sealing edge 12 for electrical connection with an external circuit.
[0059] For the electrode assembly 20, please refer to Figure 3 and Figure 4 The electrode assembly 20 includes a first electrode sheet 21, a second electrode sheet 22 and a separator 23. The first electrode sheet 21, the separator 23 and the second electrode sheet 22 are stacked and wound, for example, stacked along the thickness direction (first direction Z) of the first electrode sheet 21 and wound along its length direction (second direction X) to form a wound electrode assembly 20. The separator 23 is disposed between the first electrode sheet 21 and the second electrode sheet 22 to insulate and separate the first electrode sheet 21 and the second electrode sheet 22.
[0060] In some other embodiments, a plurality of first pole pieces 21 and a plurality of second pole pieces 22 are alternately stacked, and an isolation film 23 is disposed between adjacent first pole pieces 21 and second pole pieces 22 , thereby forming a stacked electrode assembly 20 .
[0061] The polarity of the first pole piece 21 is opposite to that of the second pole piece 22, for example, the first pole piece 21 is a positive pole piece and the second pole piece 22 is a negative pole piece, or in some other embodiments, the first pole piece 21 is a negative pole piece and the second pole piece 22 is a positive pole piece. The first pole tab 30 is connected to the first pole piece 21, and the current of the first pole piece 21 is collected and transmitted through the first pole tab 30, and the second pole tab 40 is connected to the second pole piece 22, and the current of the second pole piece 22 is collected and transmitted through the second pole tab 40, thereby leading out the positive and negative poles of the secondary battery 100.
[0062] Please refer to Figure 4 The first pole piece 21 includes a first current collector 211 and a first active material layer 212. The first current collector 211 serves as a conductive substrate of the first pole piece 21 and may be an overall flat aluminum foil. Aluminum foil has high electrical conductivity and low resistance, and can improve the maximum charge and discharge rate of the secondary battery 100. In addition, aluminum foil has certain strength and ductility. In the production process such as winding or lamination, the aluminum foil is not easy to break or deform, so as to ensure the structural integrity of the first pole piece 21. In some other embodiments, the first current collector 211 may also be made of titanium foil, nickel foil or stainless steel foil.
[0063] The first active material layer 212 can be stacked on one surface of the first current collector 211 in the thickness direction (first direction Z), and the first active material layer 212 includes a positive electrode active material, a conductive agent, and an adhesive, etc. The above-mentioned material components are mixed and stirred evenly and coated on the surface of the first current collector 211, thereby obtaining the first active material layer 212. Among them, the positive electrode active material includes one or more of lithium nickel cobalt manganese oxide, lithium cobalt oxide, lithium iron phosphate, lithium nickel cobalt manganese oxide, lithium manganese oxide, or lithium manganese iron phosphate. Optionally, the first pole piece 21 also includes a second active material layer 213, which is stacked on the other surface of the first current collector 211 in the thickness direction (first direction Z) to form a double-sided coating structure, and the second active material layer 213 can be set similarly to the first active material layer 211.
[0064] Please refer to Figure 4 The second pole piece 22 includes a second current collector 221 and a third active material layer 222. The second current collector 221 serves as a conductive substrate of the second pole piece 22 and may be a flat copper foil. The copper foil has high electrical conductivity and low resistance, and can improve the maximum charge and discharge rate of the secondary battery 100. In addition, the copper foil has certain strength and ductility. In the production process such as winding or lamination, the copper foil is not easy to break or deform, so as to ensure the structural integrity of the second pole piece 22. In some other embodiments, the second current collector 221 may also be made of titanium foil, nickel foil, stainless steel foil or silver foil.
[0065] The third active material layer 222 can be stacked on one surface of the second current collector 221 in the thickness direction (first direction Z), and the third active material layer 222 includes negative electrode active materials, conductive agents, and adhesives, etc. These materials are mixed and stirred evenly and applied to the surface of the second current collector 221 to obtain the third active material layer 222. Among them, the negative electrode active material includes one or more of graphite, soft carbon, hard carbon, carbon fiber, elemental silicon, silicon oxide, silicon alloy, etc. Optionally, the second pole piece 22 also includes a fourth active material layer 223, which is stacked on the other surface of the second current collector 221 in the thickness direction (first direction Z) to form a double-sided coating structure. The fourth active material layer 223 can be set similarly to the third active material layer 222.
[0066] For the first tab 30, please refer to Figure 1 and Figure 4 The first current collector 211 is provided with a first empty foil area 211 a (without the first active material layer 212 ), one end of the first electrode tab 30 is connected to the first empty foil area 211 a , and the other end extends out of the shell 10 from the sealing edge 12 .
[0067] In the embodiments of this application, please refer to Figure 1 and Figure 5The secondary battery 100 further includes a first seal 50, which is disposed between the first pole tab 30 and the edge seal 12. The first seal 50 can fill the gap between the first pole tab 30 and the edge seal 12, reduce the risk of leakage of the secondary battery 100, and reduce the entry of external air, moisture, dust and other substances into the secondary battery 100, thereby improving the sealing performance of the housing 10. In addition, the first seal 50 can provide a certain bonding performance, improve the bonding strength between the first pole tab 30 and the housing 10, and reduce the relative displacement between the first pole tab 30 and the housing 10.
[0068] In some embodiments, please refer to Figure 5 Along the thickness direction (first direction Z) of the first electrode tab 30, the first electrode tab 30 includes a first surface 31 and a second surface 32 that are oppositely disposed, and the first surface 31 is disposed facing the first empty foil area 211a. The first sealing member 50 includes a first portion 51, and the first portion 51 extends between the first electrode tab 30 and the first empty foil area 211a, and the first electrode tab 30 and the first empty foil area 211a are bonded through the first portion 51.
[0069] In the embodiment of the present application, the first pole ear 30 is bonded and fixed to the first empty foil area 211a by the first sealing member 50, and there are no welding burrs, which can reduce the short circuit of the secondary battery 100. There is no need to set a protective adhesive layer on the first pole ear 30 or the first empty foil area 211a to cover the burrs, thereby eliminating the space occupied by the protective adhesive layer, thereby reducing the cost and improving the energy density of the secondary battery 100.
[0070] In addition, the first seal 50 has good sealing performance, can effectively fill the small gap between the first pole tab 30 and the first empty foil area 211a, and can improve the connection strength between the first pole tab 30 and the first empty foil area 211a. A sealing layer that continuously covers the first pole tab 30 can be formed in the housing 10, which can not only improve the strength of the first pole tab 30 and reduce the tearing of the first pole tab 30, but also effectively reduce the bending and skewing of the first pole tab 30, thereby reducing the risk of short circuit between the first pole tab 30 and other components.
[0071] In addition, the bonding of the first pole tab 30 and the sealing of the housing 10 can be completed in one step. In the production process of the secondary battery 100, the first portion 51 of the first seal 50 is extended to bond the first pole tab 30 and the first empty foil area 211a of the first current collector 211, so that the bonding and sealing steps can be combined into one, reducing the production process, which is conducive to improving production efficiency and reducing production costs. In contrast, if a common bonding layer is used for bonding first and then a separate sealing process is performed, not only the production time and labor costs are increased, but also more quality risk factors may be introduced due to multiple operations.
[0072] The material of the first seal 50 can be at least one of polyethylene, polypropylene, ethylene-vinyl acetate copolymer, thermoplastic elastomer, acrylate, polyurethane or epoxy resin. Each material has good chemical stability, which can reduce the corrosion of the first seal 50 by the electrolyte. It also has better bonding performance, can form a good bond with the first pole ear 30 and the first current collector 211, and improve the connection strength between the first pole ear 30 and the first current collector 211. At the same time, it also has a certain strength and toughness, can resist a certain degree of external force impact and the volume change of the secondary battery 100 during the charge and discharge cycle, and can reduce the damage and tearing of the first pole ear 30.
[0073] For the electrical connection between the first electrode tab 30 and the first current collector 211, conductive particles may be added to the portion of the first portion 51 that is bonded to the first electrode tab 30 and the first empty foil area 211a, thereby making the first electrode tab 30 conductive with the first current collector 211. For example, adding conductive particles such as silver, copper, nickel, aluminum, graphite or carbon nanotubes may achieve electrical connection between the first electrode tab 30 and the first current collector 211.
[0074] In some other embodiments, please refer to Figure 6 The first surface 31 is provided with a plurality of first protrusions 30a, the first protrusions 30a protrude relative to the first surface 31, and the first portion 51 is partially embedded between two adjacent first protrusions 30a, which can increase the bonding area between the first pole tab 30 and the first seal 50, thereby improving the connection strength between the first pole tab 30 and the first current collector 211. At the same time, the provision of the first protrusions 30a can not only improve the strength of the first pole tab 30, but also make the first pole tab 30 have a stronger current carrying capacity, which can reduce the heat generation of the first pole tab 30 while reducing the damage and tearing of the first pole tab 30.
[0075] In some embodiments, at least part of the first protrusion 30a is in contact with the first empty foil area 211a, and the first protrusion 30a is more likely to penetrate the first portion 51 and contact the first empty foil area 211a, making it easier to achieve conduction between the first pole tab 30 and the first pole sheet 21. At the same time, a more direct conductive path can be provided. Compared with conducting current only by adding conductive particles, direct contact can significantly reduce the contact resistance between the first pole tab 30 and the first current collector 211, which is beneficial to improving the charge and discharge efficiency of the secondary battery 100.
[0076] It is understandable that when the first protrusion 30a is in direct contact with the first empty foil area 211a, the first electrode tab 30 is directly connected to the first current collector 211, and there is no need to add conductive particles to the first part 51, which is conducive to simplifying the manufacturing process and reducing production costs.
[0077] In some embodiments, please refer to Figure 7, along the first direction Z, the width of the first protrusion 30a in the second direction X or the third direction Y is reduced, the first direction Z is the direction from the first pole tab 30 to the first current collector 211, the second direction X is the length direction of the first pole piece 21, and the third direction Y is the width direction of the first pole piece 21. In the embodiment of the present application, the width of the first protrusion 30a is gradually reduced, and the resistance encountered in the process of penetrating the first seal 50 is smaller, and it is easier to penetrate the relatively soft first seal 50, reducing the excessive extrusion or damage to the first seal 50 during the penetration process. In addition, after the first protrusion 30a penetrates, it is beneficial for the first seal 50 to restore its shape around the first protrusion 30a, and then fill the gap between the two adjacent first protrusions 30a, so that the first seal 50 and the first pole tab 30 can be more closely bonded, and the connection strength between the first pole tab 30 and the first current collector 211 is improved.
[0078] In some embodiments, please refer to Figure 8 At least part of the first protrusion 30a is inserted into the first current collector 211, so that an anchor point can be formed between the first pole tab 30 and the first current collector 211, providing a more secure mechanical interlock, and effectively reducing the separation of the first pole tab 30 from the first current collector 211 caused by the first pole tab 30 when the secondary battery 100 is subjected to vibration, impact, etc. At the same time, it can provide a more direct conductive path, form a more stable electrical connection, reduce current fluctuations and energy losses caused by poor contact, and reduce the contact resistance between the first pole tab 30 and the first current collector 211, which is conducive to improving the charge and discharge rate of the secondary battery 100.
[0079] In some other embodiments, please refer to Fig. 9 , in the thickness direction (first direction Z) of the first pole piece 21, at least part of the first protrusion 30a penetrates the first current collector 211, and a more solid interlocking structure can be constructed between the first pole tab 30 and the first current collector 211, further improving the bonding strength between the first pole tab 30 and the first current collector 211, and can effectively resist strong vibration, impact and extreme acceleration changes, etc., and reduce the loosening or separation between the first pole tab 30 and the first current collector 211. It can also further reduce the contact resistance between the first pole tab 30 and the first current collector 211, which helps to improve the uniformity of current distribution on the first current collector 211 and effectively reduce local overheating.
[0080] In some embodiments, please refer to Fig.10 and Fig.11The first surface 31 is provided with a plurality of first recessed portions 30b, which are recessed relative to the first surface 31, and the first portion 51 is partially embedded in the first recessed portions 30b, which can increase the bonding area between the first pole tab 30 and the first seal 50, thereby improving the connection strength between the first pole tab 30 and the first current collector 211. At the same time, the first recessed portion 30b can be used as a storage space for the first seal 50, so that the first seal 50 is better retained between the first pole tab 30 and the first current collector 211. For example, during the thermal runaway of the secondary battery 100, the first seal 50 can be melted and depressurized, and the first recessed portion 30b can reduce the loss of the melted first seal 50. After solidification, sufficient first seal 50 can be again made between the first pole tab 30 and the first current collector 211 to achieve a good bonding effect, which is conducive to maintaining the connection stability of the first pole tab 30 and the first current collector 211 for a long time.
[0081] When the first electrode tab 30 is bonded to the first empty foil area 211a of the first current collector 211 through the first seal 50, the first surface 31 can also directly contact the first empty foil area 211a, thereby directly forming a conductive path between the first electrode tab 30 and the first current collector 211, which is beneficial to reducing contact resistance.
[0082] Please refer to Fig.12 , the first pole ear 30 has a second surface 32 away from the first empty foil area 211a, and the first seal 50 also includes a second portion 52 disposed on the second surface 32. Along the thickness direction (first direction Z) of the first pole piece 21, within the projection range of the first empty foil area 211a, the second portion 52 covers at least the first pole ear 30. The first pole ear 30 may have tiny cutting burrs, which may also pierce the isolation film. The second portion 52 can reduce the cutting burrs of the first pole ear 30 from piercing the isolation film 23, thereby reducing the occurrence of short circuits. At the same time, a double-sided fixed structure of the first pole ear 30 can be formed, reducing the relative displacement between the first pole ear 30 and the first current collector 211 and the housing 10. It also helps to improve the sealing performance of the secondary battery 100, further reducing the risk of leakage and reducing the risk of impurities such as external air and moisture entering the interior of the secondary battery 100.
[0083] In some embodiments, along the width direction (second direction X) of the first pole tab 30, the first pole tab 30 further includes a third surface 33 and a fourth surface 34 that are arranged opposite to each other, and the third surface 33 and the fourth surface 34 are both connected between the first surface 31 and the second surface 32. The first sealing member 50 further includes a third portion 53 and a fourth portion 54, and along the thickness direction (first direction Z) of the first pole piece 21, within the projection range of the first empty foil area 211a, the third portion 53 is bonded to at least a portion of the third surface 33, and the fourth portion 54 is bonded to at least a portion of the fourth surface 34. A structure in which the first sealing member 50 wraps the first pole tab 30 can be formed, and the first sealing member 50 is directly sleeved on the first pole tab 30, and the installation process is simpler.
[0084] Furthermore, the first seal 50 wraps the first pole tab 30 to form an all-round fixed structure, which is beneficial to dispersing the stress on the first pole tab 30, thereby reducing problems such as cracks or falling off of the first pole tab 30 due to stress concentration.
[0085] At the same time, the first sealant 50 wrapping the first pole ear 30 can tightly seal the space around the first pole ear 30, effectively preventing the electrolyte from leaking out of the first pole ear 30, and further reducing the external air, moisture, dust and other impurities entering the interior of the secondary battery 100, further improving the sealing performance of the secondary battery 100.
[0086] In some embodiments, please refer to Figure 4 , the first active material layer 212 is provided with a first groove 211b, and the first current collector 211 forms a first empty foil area 211a in the first groove 211b, for example, a part of the first active material layer 212 is removed by laser cleaning or foaming glue, so that the first current collector 211 is partially exposed, thereby forming the first empty foil area 211a. The first pole piece 21 also includes a second active material layer 213, and the second active material layer 213 is superimposed on the surface of the first current collector 211 away from the first active material layer 212. Along the thickness direction (first direction Z) of the first pole piece 21, the first groove 211b is located in the projection of the second active material layer 213.
[0087] In the embodiment of the present application, since the first electrode tab 30 is bonded to the first current collector 211 through the first seal 50, there is no need for a welding head and a welding seat, that is, there is no need to open a groove in the second active material layer 213 to place the welding seat, so that the structure of the second active material layer 213 is more complete, and the powder shedding of part of the second active material layer 213 caused by the grooving is reduced, so that the second active material layer 213 can be fully utilized, thereby improving the energy density of the secondary battery 100.
[0088] In addition, when the first protrusion 30a penetrates the first current collector 211, please refer to Fig. 9, the first protrusion 30a can be in direct contact with the second active material layer 213, which can shorten the conductive path, help improve the current distribution inside the second active material layer 213, promote the full reaction of the active material, improve the utilization rate of the second active material layer 213, and thus improve the energy density of the secondary battery 100.
[0089] In some embodiments, please refer to Figure 4 The second active material layer 213 includes a first region 2131. Along the thickness direction (first direction Z) of the first electrode 21, the projection of the first region 2131 coincides with the first groove 211b, and the surface of the first region 2131 facing away from the first current collector 211 is at least partially in contact with the isolation film 23.
[0090] In the embodiment of the present application, since the first electrode tab 30 is bonded to the first current collector 211 through the first sealant 50, there are no welding burrs. The first region 2131 of the second active material layer 213 does not need to have a corresponding groove, nor does it need to have a protective adhesive layer to cover the burrs. Therefore, the first region 2131 of the second active material layer 213 can directly contact the isolation membrane 23, that is, the first region 2131 can participate in the electrochemical reaction, thereby improving the energy density of the secondary battery 100.
[0091] Regarding the second pole tab 40, the second pole tab 40 may also be configured similarly to the first pole tab 30. Please refer to Figure 1 and Figure 4 The second current collector 221 is provided with a second empty foil area 221a, for example, by opening a second groove 221b on the third active material layer 222 to partially expose the second current collector 221, thereby forming the second empty foil area 221a. One end of the second electrode tab 40 is connected to the second empty foil area 221a, and the other end extends out of the housing 10 from the sealing edge 12.
[0092] In the embodiments of this application, please refer to Figure 1 and Figure 4 The secondary battery 100 further includes a second seal 60, which is disposed between the second pole tab 40 and the edge seal 12. The second seal 60 can fill the gap between the second pole tab 40 and the edge seal 12, reduce the risk of leakage of the secondary battery 100, and reduce the entry of external air, moisture, dust and other substances into the interior of the secondary battery 100, thereby improving the sealing performance of the housing 10. In addition, the second seal 60 can provide a certain bonding performance, improve the bonding strength between the second pole tab 40 and the housing 10, and reduce the relative displacement between the second pole tab 40 and the housing 10.
[0093] In some embodiments, please refer to Fig.15The second pole tab 40 includes a fifth surface 41 facing the second empty foil area 221a, and the second sealing member 60 includes a fifth portion 61, which extends between the second pole tab 40 and the second empty foil area 221a, and the second pole tab 40 and the second empty foil area 221a are bonded through the fifth portion 61.
[0094] In the embodiment of the present application, the second pole ear 40 is bonded and fixed to the second empty foil area 221a by the second sealing member 60, and there are no welding burrs, which can reduce the short circuit of the secondary battery 100. There is no need to set a protective adhesive layer on the second pole ear 40 or the second empty foil area 221a to cover the burrs, thereby eliminating the space occupied by the protective adhesive layer, thereby reducing the cost and improving the energy density of the secondary battery 100.
[0095] In addition, the second seal 60 has good sealing performance, can effectively fill the small gap between the second pole tab 40 and the first empty foil area 211a, and can improve the connection strength between the second pole tab 40 and the second empty foil area 221a. A sealing layer that continuously covers the second pole tab 40 can be formed in the housing 10, which can not only improve the strength of the second pole tab 40, reduce the tearing of the second pole tab 40, but also effectively reduce the bending or skewing of the second pole tab 40, thereby reducing the risk of short circuit between the second pole tab 40 and other components.
[0096] In addition, the bonding of the second pole tab 40 and the sealing of the shell 10 can be completed in one step. During the production process of the secondary battery 100, the second pole tab 40 and the second empty foil area 221a of the second current collector 221 are bonded by extending the fifth portion 61 of the second sealing member 60, so that the bonding and sealing steps can be combined into one, thereby reducing the production process, which is beneficial to improving production efficiency and reducing production costs.
[0097] Among them, the specific connection structure of the second electrode tab 40, the second current collector 221 and the second seal 60 can refer to the above-mentioned first electrode tab 30, the first current collector 211 and the first seal 50, and their structures are similar, so this application will not describe them one by one.
[0098] In some embodiments, taking the first electrode sheet 21 as a positive electrode sheet and the second electrode sheet 22 as a negative electrode sheet as an example, the second electrode sheet 22 includes a second current collector 221 and a third active material layer 222, and the third active material layer 222 is superimposed on the surface of the second current collector 221 facing the first active material layer 212. The third active material layer 222 includes a second region 2221, and along the thickness direction (first direction Z) of the first electrode sheet 21, the projection of the second region 2221 coincides with the first groove 211b, and the surface of the second region 2221 facing the first groove 211b is at least partially in contact with the isolation film 23.
[0099] In the embodiment of the present application, since the first pole tab 30 is bonded to the first current collector 211 through the first seal 50, there is no welding burr, and the risk of piercing the separator 23 is low. Therefore, the second region 2221 of the third active material layer 222 does not need to be provided with a protective adhesive layer, so that the second region 2221 can participate in the electrochemical reaction normally, thereby improving the energy density of the secondary battery 100. In addition, since the second pole piece 22 is a negative pole piece, the second pole piece 22 can have sufficient margin to embed the lithium ions released from the first pole piece 21, thereby reducing the occurrence of lithium plating.
[0100] In the second aspect, the present application also proposes an electronic device, including a secondary battery 100 as described in any embodiment of the first aspect above. The electronic device of the embodiment of the present application is not particularly limited, and it can be any electronic device known in the prior art. For example, electronic devices include but are not limited to Bluetooth headsets, mobile phones, tablets, laptops, electric toys, electric tools, battery cars, electric cars, ships, spacecraft, etc. Among them, electric toys can include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc., and spacecraft can include airplanes, rockets, space shuttles, and spacecrafts, etc.
[0101] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Under the concept of the present application, the technical features in the above embodiments or different embodiments may also be combined, the steps may be implemented in any order, and there are many other changes in different aspects of the present application as described above, which are not provided in detail for the sake of simplicity. Although the present application has been described in detail with reference to the aforementioned embodiments, a person of ordinary skill in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.
Claims
1. A secondary battery, comprising a shell, an electrode assembly and a first pole ear, wherein the shell is provided with a sealed edge, and the electrode assembly is arranged in the shell; the electrode assembly comprises a first pole sheet, the first pole sheet comprises a first current collector and a first active material layer superimposed on the surface of the first current collector, the first current collector is provided with a first empty foil area, one end of the first pole ear is arranged in the first empty foil area, and the other end extends out of the shell from the sealed edge, characterized in that: A first sealing member is provided between the first electrode tab and the sealing edge; The first electrode tab includes a first surface facing the first empty foil area, the first seal includes a first portion disposed on the first surface, the first portion extends between the first electrode tab and the first empty foil area, and the first electrode tab and the first empty foil area are bonded via the first portion.
2. The secondary battery according to claim 1, characterized in that: The first surface is provided with a plurality of first protrusions, the first protrusions protrude relative to the first surface, and the first portion is partially embedded between two adjacent first protrusions.
3. The secondary battery according to claim 2, characterized in that: At least a portion of the first protrusion is in contact with the first empty foil area.
4. The secondary battery according to claim 2 or 3, characterized in that: Along the first direction, the first protrusion is arranged with a reduced width in the second direction; The first direction is the direction from the first pole tab to the first current collector, and the second direction is the length or width direction of the first pole piece.
5. The secondary battery according to claim 4, characterized in that: At least a portion of the first protrusion is inserted into the first current collector.
6. The secondary battery according to claim 5, characterized in that: Along the thickness direction of the first pole piece, at least a portion of the first protrusion penetrates the first current collector.
7. The secondary battery according to claim 1, characterized in that: The first surface is provided with a plurality of first recessed parts, the first recessed parts are recessed relative to the first surface, and the first part is partially embedded in the first recessed parts.
8. The secondary battery according to claim 1, characterized in that: The first electrode tab has a second surface facing away from the first empty foil area; The first sealing member further includes a second portion disposed on the second surface, and along the thickness direction of the first pole piece, within the projection range of the first empty foil area, the second portion covers at least a portion of the first pole tab.
9. The secondary battery according to claim 8, characterized in that: Along the width direction of the first electrode tab, the first electrode tab further includes a third surface and a fourth surface that are arranged opposite to each other, and the third surface and the fourth surface are both connected between the first surface and the second surface; The first seal also includes a third part and a fourth part. Along the thickness direction of the first pole piece, within the projection range of the first empty foil area, the third part is bonded to at least a portion of the third surface, and the fourth part is bonded to at least a portion of the fourth surface.
10. The secondary battery according to claim 1, characterized in that: The first active material layer is provided with a first groove, and the first current collector forms the first empty foil area in the first groove; The first pole piece further includes a second active material layer, and the second active material layer is stacked on a surface of the first current collector away from the first active material layer; Along the thickness direction of the first pole piece, the first groove is located within the projection of the second active material layer.
11. The secondary battery according to claim 10, characterized in that: The secondary battery further comprises a separator and a second pole piece, wherein the separator is disposed between the first pole piece and the second pole piece along a thickness direction of the first pole piece; The second active material layer includes a first region, a projection of the first region coincides with the first groove along the thickness direction of the first pole piece, and a surface of the first region facing away from the first current collector is at least partially in contact with the isolation film.
12. The secondary battery according to claim 10, characterized in that: The secondary battery further comprises a separator and a second pole piece, wherein the separator is disposed between the first pole piece and the second pole piece along the thickness direction of the first pole piece, the first pole piece is a positive pole piece, and the second pole piece is a negative pole piece; The second pole piece includes a second current collector and a third active material layer, and the third active material layer is stacked on a surface of the second current collector facing the first active material layer; The third active material layer includes a second region, a projection of the second region coincides with the first groove along the thickness direction of the first pole piece, and a surface of the second region facing the first groove at least partially contacts the isolation film.
13. The secondary battery according to claim 12, characterized in that: The secondary battery further includes a second electrode tab and a second sealing member; The second current collector is provided with a second empty foil area, one end of the second pole tab is connected to the second empty foil area, and the other end extends out of the shell from the edge seal, and the second sealing member is provided between the second pole tab and the edge seal; The second electrode tab includes a fifth surface facing the second empty foil area, the second sealing member includes a fifth portion, the fifth portion extends between the second electrode tab and the second empty foil area, and the second electrode tab and the second empty foil area are bonded via the fifth portion.
14. An electronic device, characterized in that: The invention comprises the secondary battery according to any one of claims 1 to 13.