Tab assembly, secondary battery, electronic equipment and method for preparing secondary battery

Abstract

The embodiment of the invention relates to the technical field of energy storage, and discloses a tab assembly, a secondary battery, electronic equipment and a method for preparing the secondary battery, the tab assembly comprises an adapter tab and a bonding piece, the adapter tab comprises an internal connection section and an adhesive section along the extension direction of the adapter tab, one end of the adhesive section is connected with the internal connection section, and the other end of the adhesive section is connected with the secondary battery. The internal connection section is used for being electrically connected with a battery cell, the bonding part wraps the bonding section and is bonded and fixed with the bonding section, a first groove is formed in the part, bonded to the bonding section, of the bonding part, the first groove is located in the edge, facing the internal connection section, of the bonding part, and a notch of the first groove faces the internal connection section. Through the mode, when the tab assembly and the inner tab of the battery cell are welded, the risk that the bonding piece covers the internal connecting section can be reduced, and then the risk of pseudo soldering between the inner tab and the switching tab is reduced.

Description

Technical Field

[0001] The embodiments of the present application relate to the technical field of energy storage, and particularly to an ear component, a secondary battery, an electronic device, and a method for manufacturing a secondary battery. Background Art

[0002] With the rapid development of modern technology, the demand for high-performance energy storage devices in fields such as portable electronic devices and electric vehicles is increasing day by day. As an efficient and environmentally friendly energy storage device, lithium-ion batteries have been widely used in many fields due to their high energy density, long cycle life, low self-discharge rate, etc.

[0003] The ear component is used to connect the inner ear of the battery cell, and the stability of the connection between the ear component and the inner ear is related to the safety performance and service life of the lithium-ion battery. Therefore, how to improve the stability of the connection between the ear component and the inner ear has become a research hotspot. Summary of the Invention

[0004] The main technical problem to be solved by the embodiments of the present application is to provide an ear component, a secondary battery, an electronic device, and a method for manufacturing a secondary battery, which can reduce the risk of the bonding member covering the internal connection section when welding the ear component to the inner ear of the battery cell, and further reduce the risk of virtual welding between the inner ear and the transfer ear.

[0005] In a first aspect, the present application provides an ear component, including an internal connection section and an adhesive section. One end of the adhesive section is connected to the internal connection section. The internal connection section is used for electrically connecting with the battery cell. The bonding member wraps the adhesive section and is bonded and fixed to the adhesive section. A first groove is provided in the part of the bonding member bonded to the adhesive section. The first groove is located at an edge of the bonding member facing the internal connection section, and the notch of the first groove faces the internal connection section.

[0006] In this embodiment, by providing the first groove, when the bonding member is compounded to the transfer ear, the risk of the bonding member spreading along the extension direction of the transfer ear to the internal connection section can be reduced. Furthermore, during the process of welding and fixing the internal connection section to the inner ear of the battery cell, the influence of the bonding member on the welding between the internal connection section and the inner ear can be reduced, and the occurrence of virtual welding can be reduced, which is beneficial to improving the stability of the connection between the internal connection section and the inner ear. In addition, when the ear component and the battery cell are placed in a packaging bag and the sealing part of the packaging bag is heat-sealed, the overflow of glue between the ear component and the sealing part can be reduced, which is beneficial to making the sealing glue at the bonding member and the sealing part melt more fully, thereby reducing microcracks or pores, improving the sealing performance between the sealing part and the transfer ear, and further reducing the risk of electrolyte leakage in the packaging bag.

[0007] In some embodiments, along the thickness direction of the adapter ear, the adhesive section includes a first surface and a second surface arranged opposite to each other; part of the adhesive is bonded to the first surface, and part of the adhesive is bonded to the second surface; a first groove is provided at the portion of the adhesive bonded to the first surface, and a second groove is provided at the portion of the adhesive bonded to the second surface, and the second groove is located at an edge of the adhesive facing the internal connecting section, and the notch of the second groove faces the internal connecting section.

[0008] In this embodiment, by providing a second groove in the portion where the adhesive is bonded to the second surface, the risk of the adhesive spreading too much to the internal connecting section can be reduced during the process of compounding the adhesive to the adhesive section. Thus, when the packaging portion of the packaging bag is heat-sealed, the overflow of glue between the adapter ear and the packaging portion can be reduced, which is beneficial to improving the sealing performance between the adapter ear and the packaging portion.

[0009] In some embodiments, the transfer tab includes an external connection segment, and along the extension direction of the transfer tab, the external connection segment is connected to an end of the adhesive segment away from the internal connection segment;

[0010] The adhesive is provided with a third groove, and along the thickness direction of the adapter ear, the adhesive section includes a first surface and a second surface arranged oppositely, part of the adhesive is bonded to the first surface, the first groove and the third groove are both arranged at the part where the adhesive is bonded to the first surface, the first groove and the third groove are arranged oppositely along the extension direction of the adapter ear, the third groove is located at an edge of the adhesive facing the external connection section, and the notch of the third groove faces the external connection section.

[0011] In this embodiment, when the adhesive is compounded to the adapter ear, the risk of the adhesive spreading too much to the external connection section along the extension direction of the adapter ear can be reduced, thereby reducing the adhesive affecting the welding between the external connection section and the circuit board, and reducing the risk of cold solder joints between the external connection section and the circuit board; in addition, when the packaging part is heat-sealed, the overflow of glue between the first surface and the packaging part can be reduced, thereby improving the sealing performance between the first surface and the packaging part.

[0012] In some embodiments, part of the adhesive is bonded to the second surface, and the portion of the adhesive bonded to the second surface is provided with a fourth groove, which is located at an edge of the adhesive facing the external connection section, and the notch of the fourth groove faces the external connection section.

[0013] In this embodiment, when the adhesive is compounded to the adapter ear, the risk of the adhesive spreading to the external connection section along the extension direction of the adapter ear can be reduced, thereby reducing the adhesive affecting the welding between the external connection section and the circuit board, and reducing the risk of cold solder joints between the external connection section and the circuit board; in addition, when the packaging part is heat-sealed, the overflow of glue between the second surface and the packaging part can be reduced, thereby improving the sealing performance between the second surface and the packaging part.

[0014] In some embodiments, along the width direction of the transfer tab, the size of the adhesive section is L1, the size of the first groove is L2, and 0.9 ≤ L2 / L1 ≤ 1.1. Preferably, 0.95 ≤ L2 / L1 ≤ 1.05.

[0015] If the ratio between L2 and L1 is too small, when the bonding member is compounded to the adhesive section, the bonding member is likely to spread to the internal connection section, thereby affecting the welding between the internal connection section and the internal tab. Moreover, when heat-sealing the encapsulation part, the bonding member further spreads to the internal connection section, thus easily forming glue overflow. If the ratio between L2 and L1 is too large, it is likely to result in insufficient bonding area between the bonding member and the adhesive section, affecting the stability of the connection between the bonding member and the adhesive section. Also, when encapsulating the encapsulation part, it is likely to cause poor encapsulation between the transfer tab and the encapsulation part, with insufficient sealing between the transfer tab and the encapsulation part and a risk of liquid leakage. Therefore, setting 0.9 ≤ L2 / L1 ≤ 1.1 can reduce the glue overflow between the transfer tab and the encapsulation part, balance the risk of poor encapsulation, and improve the sealing performance between the transfer tab and the encapsulation part.

[0016] In some embodiments, along the extension direction of the transfer tab, the depth of the first groove is W1, and 0 < W1 ≤ 0.8 mm. Preferably, 0 < W1 ≤ 0.5 mm. Further preferably, 0 < W1 ≤ 0.3 mm. Further preferably, 0.1 mm ≤ W1 ≤ 0.3 mm.

[0017] Setting 0 < W1 can reduce the risk of the bonding member spreading to the first welding area of the welding part during the process of compounding the bonding member to the transfer tab, which is beneficial to reducing the risk of false soldering between the welding part and the internal tab. Also, when encapsulating the encapsulation part, it can reduce the glue overflow between the transfer tab and the encapsulation part. If the depth W1 of the first groove is too large, when heat-sealing the encapsulation part, there is a lack of bonding member between the transfer tab and the encapsulation part at the first groove, thus forming a depression, resulting in poor encapsulation between the transfer tab and the encapsulation part and affecting the sealing performance of the encapsulation part. Setting W1 ≤ 0.8 mm can reduce the risk of forming a depression between the transfer tab and the encapsulation part at the first groove during the heat-sealing process of the encapsulation part, which is beneficial to improving the sealing performance of the encapsulation part.

[0018] In some embodiments, along the extension direction of the transfer tab, the depth of the third groove is W2, and 0 < W2 ≤ 1 mm. Preferably, 0.1 mm ≤ W2 ≤ 0.8 mm. Further preferably, 0.3 mm ≤ W2 ≤ 0.5 mm.

[0019] Setting 0 < W2 can reduce the risk that the bonding member spreads to the external connection section along the length direction of the transfer tab during the process of the bonding member being compounded to the transfer tab, which is beneficial to reducing the risk of poor soldering when the external connection section is soldered to the circuit board, thereby improving the connection stability between the external connection section and the circuit board. And when encapsulating the encapsulation part of the packaging bag, it can reduce the glue overflow between the transfer tab and the encapsulation part; if W2 is too large, when heat-sealing the encapsulation part, there is a lack of bonding member material between the transfer tab and the encapsulation part at the third groove, thus forming a depression, resulting in poor encapsulation between the transfer tab and the encapsulation part and affecting the sealing performance of the encapsulation part. Setting W2 ≤ 1 mm can reduce the risk of forming a depression between the transfer tab and the encapsulation part at the third groove during the heat-sealing process of the encapsulation part, which is beneficial to improving the sealing performance of the encapsulation part.

[0020] In a second aspect, the present application provides a secondary battery, including a battery cell, a packaging bag, and the above-mentioned tab assembly. The battery cell is accommodated in the packaging bag. The battery cell is provided with an internal tab, and the internal connection section is connected to the internal tab. The packaging bag is provided with an encapsulation part, and the transfer tab penetrates through the encapsulation part, and at least part of the transfer tab protrudes outside the packaging bag.

[0021] In some embodiments, along the width direction of the transfer tab, the bonding member includes a protruding part and a bonding part that are sequentially connected. The bonding part is the part that overlaps with the transfer tab, and the protruding part is the part located outside the transfer tab. Along the extending direction of the transfer tab, the protruding part has a first edge and a second edge that are oppositely arranged. The bonding part has a third edge and a fourth edge that are oppositely arranged. The third edge is closer to the first edge than the fourth edge, and the third edge is closer to the internal connection section than the fourth edge; define a first tangent line, the first tangent line extends along the width direction of the transfer tab, and the first tangent line is tangent to the position of the third edge farthest from the first edge; along the extending direction of the transfer tab, the distance between the first edge and the second edge is W3, and the distance between the first tangent line and the second edge is W4, -0.2 mm ≤ W3 - W4 ≤ 0.5 mm.

[0022] If the value of W3 - W4 is too small, it is easy to cause the distance between the bonding member and the first welding area to be too close, and even part of the bonding member covers the first welding area, affecting the soldering between the first welding area and the internal tab; if the value of W3 - W4 is too large, it is easy to cause a lack of bonding material between the transfer tab and the encapsulation part, thus forming a large-area depression, resulting in a significant decrease in the sealing performance of the encapsulation part. Therefore, setting -0.2 mm ≤ W3 - W4 can reduce the risk of the bonding member spreading to the first welding area, which is beneficial to reducing the risk of poor soldering between the internal tab and the first welding area, and can reduce the glue overflow between the transfer tab and the encapsulation part; setting W3 - W4 ≤ 0.5 mm can reduce the depression area between the transfer tab and the encapsulation part and improve the sealing performance of the encapsulation part.

[0023] In some embodiments, -0.1 mm ≤ W3-W4 ≤ 0.3 mm. More preferably, 0 ≤ W3-W4 ≤ 0.3 mm.

[0024] In some embodiments, the average thickness of the bonding portion within 0.1 mm of the third edge is less than the average thickness of the protruding portion.

[0025] In some embodiments, the internal connecting segment is provided with a first welding area, the inner tab and the internal connecting segment are welded and fixed in the first welding area, and along the extension direction of the transfer tab, the minimum distance from an edge of the first welding area to the first tangent is W5, 0.2mm≤W5≤1mm.

[0026] If the value of W5 is too small, the adhesive will easily affect the welding between the first welding area and the inner pole ear, resulting in a greater risk of cold welding, which will lead to a decrease in the welding tension between the first welding area and the inner pole ear; if the value of W5 is too large, the risk of cold welding between the first welding area and the root of the inner pole ear will increase under the premise that the size of the first welding area remains unchanged, which will also easily lead to a decrease in welding tension. Therefore, setting 0.2mm≤W5≤1mm can reduce the risk of cold welding between the first welding area and the inner pole ear, which is conducive to improving the welding tension between the first welding area and the inner pole ear.

[0027] In some embodiments, the transfer tab further includes an external connection segment, and along the extension direction of the transfer tab, the external connection segment is connected to one end of the adhesive segment away from the internal connection segment; the secondary battery further includes a circuit board, and the circuit board is connected to the external connection segment; a second tangent is defined, and the second tangent extends along the width direction of the transfer tab, and the second tangent is tangent to the position of the fourth edge farthest from the second edge; along the extension direction of the transfer tab, the spacing between the second tangent and the first edge is W6, -0.8mm≤W3-W6≤0.8mm. Preferably, -0.5mm≤W3-W6≤0.5mm. More preferably, -0.3mm≤W3-W6≤0.3mm. More preferably, 0≤W3-W6≤0.3mm.

[0028] If the value of W3-W6 is too small, it means that the distance between the bonding piece and the welding position of the external connection section and the circuit board is too small, which is easy to increase the risk of cold welding between the external connection section and the circuit board; if the value of W3-W6 is too large, it is easy to cause the bonding piece between the adapter tab and the packaging part to form a large depression area, resulting in a decrease in sealing performance. Therefore, setting -0.8mm≤W3-W6 is conducive to reducing the risk of cold welding between the external connection section and the circuit board, thereby increasing the welding tension between the external connection section and the circuit board; setting W3-W6≤0.8mm can reduce the area of ​​the depression formed by the bonding piece between the adapter tab and the packaging part, which is conducive to increasing the welding tension between the external connection section and the circuit board.

[0029] In some embodiments, the average thickness of the bonding portion within 0.1 mm of the fourth edge is less than the average thickness of the protruding portion.

[0030] In a third aspect, the present application provides an electronic device, comprising the above-mentioned secondary battery.

[0031] In a fourth aspect, the present application provides a method for preparing a secondary battery, comprising:

[0032] A battery cell, a packaging film and the above-mentioned tab assembly are provided, wherein the battery cell is provided with an inner tab, the packaging film is provided with a pit for accommodating the battery cell, and the edge of the packaging film is provided with a first sealant and a second sealant;

[0033] Weld and fix the internal connection section to the inner pole ear;

[0034] The battery cell is placed in the pit, wherein, when viewed along the thickness direction of the adhesive, the orthographic projection of the adhesive bonded to the adhesive section at least partially overlaps with the orthographic projection of the first sealant or the second sealant, and the transfer tab at least partially protrudes from the edge of the packaging film;

[0035] Folding the packaging film so that the first sealant and the second sealant overlap each other, wherein the transfer tab extends out from between the first sealant and the second sealant, and the adhesive member is located between the first sealant and the second sealant;

[0036] The first sealant, the second sealant and the adhesive are hot-melted to form a secondary battery.

[0037] In this embodiment, an avoidance groove is formed at the cut by cutting the edge of the adhesive in the width direction of the adhesive, and the notch of the avoidance groove faces the edge in the width direction of the adhesive. On the one hand, in the process of hot-melting the adhesive to the bonding section, the risk of the adhesive spreading to the internal connecting section can be reduced, thereby reducing the risk of cold welding between the internal connecting section and the inner pole ear; on the other hand, in the process of hot-melting the first sealant, the second sealant and the adhesive, the formation of overflow can be reduced.

[0038] The beneficial effects of the embodiments of the present application are as follows: different from the prior art, in the embodiments of the present application, by setting the first groove, when the adhesive is compounded to the adapter lug, the risk of the adhesive spreading to the internal connecting section along the extension direction of the adapter lug can be reduced, and then in the process of welding and fixing the internal connecting section to the inner lug of the battery cell, the influence of the adhesive on the welding between the internal connecting section and the inner lug can be reduced, and the occurrence of cold welding can be reduced, which is beneficial to improving the stability of the connection between the internal connecting section and the inner lug; in addition, when the lug assembly and the battery cell are placed in a packaging bag and the packaging part of the packaging bag is heat-sealed, the glue overflow between the lug assembly and the packaging part can be reduced, which is beneficial to make the sealant at the adhesive and the packaging part more fully hot-melted, thereby reducing microcracks or pores, improving the sealing performance between the packaging part and the adapter lug, and thus reducing the risk of electrolyte leakage in the packaging bag. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the following is a brief introduction to the drawings required for the specific embodiments or the prior art description. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn according to the actual scale.

[0040] Figure 1 It is a structural schematic diagram of a tab assembly in the prior art;

[0041] Figure 2 is a schematic structural diagram of a tab assembly provided in an embodiment of the present application at a first viewing angle;

[0042] Figure 3 is a schematic structural diagram of a tab assembly provided in an embodiment of the present application at a first viewing angle;

[0043] Figure 4 is a schematic structural diagram of a tab assembly provided in an embodiment of the present application at a second viewing angle;

[0044] Figure 5 is a schematic structural diagram of a secondary battery provided in an embodiment of the present application;

[0045] Figure 6 is along Figure 5 Schematic diagram of the local structure after AA sectioning;

[0046] Figure 7 is a schematic structural diagram of the tab assembly after the tab assembly and the packaging portion of the packaging bag are heat-sealed in an embodiment of the present application;

[0047] Figure 8 is a schematic diagram of the process of preparing a secondary battery provided in the embodiments of the present application;

[0048] Figure 9 It is a schematic diagram of the structure when the adhesive member of the embodiment of the present application is not compounded to the transfer tab.

[0049] Description of symbols

[0050] 100. Secondary battery;

[0051] 1. Tab assembly; 11. Transfer tab; 111. Internal connection section; 1111. Welding portion; 1112. Connecting portion; 1113. First welding region; 112. Adhesive section; 1121. First surface; 1122. Second surface; 113. External connection section; 12. Adhesive member; 1201. First groove; 1202. Second groove; 1203. Third groove; 1204. Fourth groove; 1205. Adhesive portion; 1206. Protrusion;

[0052] 2. Battery cell; 21. Inner tab; 211. U slot; 22. Anode pole piece; 23. Diaphragm; 24. Cathode pole piece;

[0053] 3. Packaging bag; 31. Packaging unit;

[0054] F, first tangent; H, second tangent. DETAILED DESCRIPTION

[0055] In order to facilitate the understanding of the present application, the present application is described in more detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that when an element is described as "fixed to" another element, it can be directly on another element or there can be one or more centered elements therebetween. When an element is described as "connected" to another element, it can be directly connected to another element or there can be one or more centered elements therebetween. The orientation or positional relationship indicated by the terms "upper", "lower", "inner", "outer", "vertical", "horizontal", etc. used in this specification is based on the orientation or positional relationship shown in the accompanying drawings, only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present application. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0056] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used in this specification includes any and all combinations of one or more of the related listed items.

[0057] In addition, 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.

[0058] In the related art, please refer to Figure 1 , Figure 1 In [reference document], the dashed line F' represents the boundary of the spreading area of the tab glue 2' after the tab glue 2' is compounded onto the tab 1'. The tab assembly 100' includes a tab 1' and a tab glue 2'. The tab 1' is used to weld with the internal tab of the battery cell. The tab glue 2' needs to wrap around the tab 1' at least once along the width direction of the tab 1' so that during the heat sealing process of the packaging bag, the tab glue 1' can be fused with the sealant at the sealing part of the packaging bag to achieve the sealing of the packaging bag. However, in the above-mentioned method, during the process of compounding the tab glue 1' onto the tab 1', the tab glue 1' is prone to spread outward along the extension direction of the tab 1', resulting in part of the tab glue 1' covering the area 3' of the tab 1' used for welding with the internal tab, which is likely to cause poor welding, thereby reducing the connection stability between the tab 1' and the internal tab.

[0059] To at least partially solve the above problems, the present application provides a tab assembly, a secondary battery, an electronic device, and a method for manufacturing a secondary battery. By providing a first groove on the bonding member, when the bonding member is compounded onto the adapter tab, the risk of the bonding member spreading to the internal connection section can be reduced, thereby reducing the risk of poor welding between the internal connection section and the internal tab, which is beneficial to improving the connection stability between the internal connection section and the internal tab.

[0060] The specific structure and function of the present application are described in detail below.

[0061] In a first aspect, the present application provides a tab assembly 1. Please refer to Figure 2 , along the width direction Y of the adapter tab 11, the bonding member 12 located outside the adapter tab is a protruding portion 1206, and the bonding member 12 overlapping with the adapter tab is a bonding portion 1205. The protruding portion 1206 has a first edge 1207 and a second edge 1208 oppositely arranged along the extension direction X of the adapter tab 11. Both the first edge 1207 and the second edge 1208 extend along the width direction Y of the adapter tab 11. The extension lines of the first edge 1207 and the second edge 1208 along the width direction Y of the adapter tab 11 divide the adapter tab 11 into an internal connection section 111, an adhesive section 112, and an external connection section 113. The tab assembly 1 includes an adapter tab 11 and a bonding member 12. The adapter tab 11 includes an internal connection section 111 and an adhesive section 112. Please refer to Figure 6, one end of the adhesive section 112 is connected to the internal connection section 111, and the internal connection section 111 is used for electrically connecting with the internal tab 21 of the battery cell 2 (the specific structure of the battery cell 2 will be described below). The bonding member 12 wraps the adhesive section 112, and the bonding member 12 is bonded and fixed to the adhesive section 112. The adhesive section 112 is used to pass through the encapsulation part 31 of the packaging bag 3 so that at least part of the transfer tab 11 protrudes outside the packaging bag 3 (the specific structure and function of the packaging bag 3 and the encapsulation part 31 will be described below), facilitating the connection of the transfer tab 11 with other components.

[0062] Please refer to Figure 2 , a first groove 1201 is provided in the part where the bonding member 12 is bonded to the adhesive section 112. The first groove 1201 is provided on one edge of the bonding member 12 facing the internal connection section 111, and the notch of the first groove 1201 faces the internal connection section 111. In the embodiment of the present application, by providing the first groove 1201 in the part where the bonding member 12 is bonded to the adhesive section 112 and the notch of the first groove 1201 faces the internal connection section 111, when the bonding member 12 is compounded to the adhesive section 112 of the transfer tab 11, even if the bonding member 12 spreads outward along the extension direction X of the transfer tab 11, the risk of the bonding member 12 spreading to cover too much of the internal connection section 111 can be reduced. Thus, during the process of welding and fixing the internal connection section 111 to the battery cell 2, the influence of the bonding member 12 on the welding between the internal connection section 111 and the internal tab 21 of the battery cell 2 can be reduced, and the occurrence of false soldering can be reduced, which is beneficial to improving the connection strength between the internal connection section 111 and the battery cell 2.

[0063] It should be noted that, please combine Figure 2 and Figure 6 , during the process of heat-sealing the packaging bag 3 of the secondary battery 100 (the specific structure of the secondary battery 100 will be described in detail below), the bonding member 12 is prone to further spread outward along the extension direction X of the transfer tab 11, thus easily causing glue overflow between the transfer tab 11 and the encapsulation part 31 of the packaging bag 3. The glue overflow is likely to cause insufficient heat fusion of the bonding member 12 between the encapsulation part 31 and the transfer tab 11 and the sealant on the encapsulation part 31, forming microcracks or pores, affecting the sealing performance between the encapsulation part 31 and the transfer tab 11, and easily resulting in the leakage of the electrolyte in the packaging bag 3. In this embodiment, by providing the first groove 1201, when the tab assembly 1 and the battery cell 2 are placed in the packaging bag 3 and the encapsulation part 31 of the packaging bag 3 is heat-sealed, the glue overflow between the tab assembly 1 and the encapsulation part 31 can be reduced, which is beneficial to making the heat fusion of the bonding member 12 and the sealant at the encapsulation part 31 more sufficient, thereby reducing microcracks or pores, improving the sealing performance between the encapsulation part 31 and the transfer tab 11, and further reducing the risk of electrolyte leakage in the packaging bag 3.

[0064] In some embodiments, refer to Figure 3 and Figure 6 , along the width direction Y of the transfer tab 11, the size of the adhesive section 112 is L1, and the size of the first groove 1201 is L2, and 0.9 ≤ L2 / L1 ≤ 1.1 is satisfied. If the ratio between L2 and L1 is too small, when the bonding member 12 is compounded to the adhesive section 112, the bonding member 12 easily spreads to the internal connection section 111, thereby affecting the welding between the internal connection section 111 and the inner tab 21. Moreover, when heat-sealing the encapsulation part 31, the bonding member 12 further spreads to the internal connection section 111, thus easily forming glue overflow; if the ratio between L2 and L1 is too large, it easily leads to insufficient bonding area between the bonding member 12 and the adhesive section 112, affecting the stability of the connection between the bonding member 12 and the adhesive section 112. Also, when encapsulating the encapsulation part 31, it easily causes poor encapsulation between the transfer tab 11 and the encapsulation part 31, resulting in insufficient sealing between the transfer tab 11 and the encapsulation part 31, and there is a risk of liquid leakage. Therefore, setting 0.9 ≤ L2 / L1 ≤ 1.1 can reduce the glue overflow between the transfer tab 11 and the encapsulation part 31, taking into account reducing the risk of poor encapsulation and improving the sealing performance between the transfer tab 11 and the encapsulation part 31.

[0065] Furthermore, along the width direction Y of the transfer tab 11, the size L1 of the adhesive section 112 and the size L2 of the first groove 1201 satisfy 0.95 ≤ L2 / L1 ≤ 1.05. Setting 0.95 ≤ L2 / L1 can further reduce the glue overflow between the transfer tab 11 and the encapsulation part 31; setting L2 / L1 ≤ 1.05 can further reduce the risk of poor encapsulation between the transfer tab 11 and the encapsulation part 31 and improve the sealing performance between the encapsulation part 31 and the transfer tab 11.

[0066] Furthermore, along the width direction Y of the transfer tab 11, the size L1 of the adhesive section 112 and the size L2 of the first groove 1201 satisfy 0.98 ≤ L2 / L1 ≤ 1.02. Setting 0.98 ≤ L2 / L1 can further reduce the glue overflow between the transfer tab 11 and the encapsulation part 31; setting L2 / L1 ≤ 1.02 can further reduce the risk of poor encapsulation between the transfer tab 11 and the encapsulation part 31 and improve the sealing performance between the encapsulation part 31 and the transfer tab 11.

[0067] In some embodiments, refer to Figure 3 and Figure 6, along the extension direction X of the transfer tab 11, the depth of the first groove 1201 is W1, and 0 < W1 ≤ 0.8 mm. If the depth W1 of the first groove 1201 is too large, when heat-sealing the encapsulation part 31, there is a lack of the bonding member 12 between the transfer tab 11 and the encapsulation part 31 at the first groove 1201, thus forming a depression, resulting in poor encapsulation between the transfer tab 11 and the encapsulation part 31 and affecting the sealing performance of the encapsulation part 31. Therefore, setting 0 < W1 can reduce the risk that the bonding member 12 spreads to the first welding area 1113 of the welding part 1111 during the process of compounding the bonding member 12 to the transfer tab 11, which is beneficial to reducing the risk of false soldering between the welding part 1111 and the inner tab 21, and when encapsulating the encapsulation part 31, it can reduce the overflow of glue between the transfer tab 11 and the encapsulation part 31. Among them, the first welding area 1113 is used for welding with the inner tab 21; setting W1 ≤ 0.8 mm can reduce the risk of forming a depression between the transfer tab 11 and the encapsulation part 31 at the first groove 1201 during the heat-sealing process of the encapsulation part 31, which is beneficial to improving the sealing performance of the encapsulation part 31.

[0068] In some embodiments, the shape of the first groove 1201 can be arc-shaped, semi-elliptical, rectangular, triangular, etc., and the present application does not limit this.

[0069] It should be noted that the bonding member 12 includes a bonding part 1205 and a protruding part 1206. The bonding part 1205 and the protruding part 1206 are arranged along the width direction Y of the transfer tab 11. One end of the bonding part 1205 is connected to one end of the protruding part 1206. The above-mentioned first groove 1201 is provided in the bonding part 1205. Along the extension direction X of the transfer tab 11, the protruding part 1206 has opposite first edge 1207 and second edge 1208. The first edge 1207 is closer to the first groove 1201 than the second edge 1208, and one end of the first edge 1207 is butted against the edge of the first groove 1201. It should be noted that the depth W1 of the above-mentioned first groove 1201 refers to the distance between the deepest part of the first groove 1201 and the first edge 1207 along the extension direction X of the transfer tab 11.

[0070] Further, along the extension direction X of the transfer tab 11, the depth W1 of the first groove 1201 satisfies 0 < W1 ≤ 0.5 mm. Setting 0 < W1 ≤ 0.5 mm is beneficial to further improving the sealing performance of the encapsulation part 31.

[0071] Further, along the extension direction X of the transfer tab 11, the depth W1 of the first groove 1201 satisfies 0 < W1 ≤ 0.3 mm. Setting 0 < W1 ≤ 0.3 mm is beneficial to further improving the sealing performance of the encapsulation part 31.

[0072] Further, along the extension direction X of the transfer tab 11, the depth W1 of the first groove 1201 satisfies 0.1 ≤ W1 ≤ 0.3 mm. Setting 0.1 ≤ W1 ≤ 0.3 mm can further reduce the risk that the bonding member 12 spreads to the first welding area 1113 of the welding part 1111 during the process of the bonding member 12 being compounded to the transfer tab 11, which is beneficial to further reducing the risk of poor soldering between the welding part 1111 and the inner tab 21. Moreover, when encapsulating the encapsulation part 31, it can further reduce the glue overflow between the transfer tab 11 and the encapsulation part 31.

[0073] In some embodiments, please refer to Figure 4 and Figure 6 , along the thickness direction Z of the transfer tab 11, the adhesive section 112 includes a first surface 1121 and a second surface 1122 which are oppositely arranged. Part of the bonding member 12 is bonded to the first surface 1121, and part of the bonding member 12 is bonded to the second surface 1122. That is to say, a part of the bonding part 1205 is bonded to the first surface 1121, and the other part is bonded to the second surface 1122. The above-mentioned first groove 1201 is provided in the part where the bonding member 12 is bonded to the first surface 1121. A second groove 1202 is provided in the part where the bonding member 12 is bonded to the second surface 1122. The second groove 1202 is located at an edge of the bonding member 12 facing the internal connection section 111, and the notch of the second groove 1202 faces the internal connection section 111. In this embodiment, by providing the second groove 1202 in the part where the bonding member 12 is bonded to the second surface 1122, during the process of compounding the bonding member 12 to the adhesive section 112, the risk that the bonding member 12 spreads to the internal connection section 111 can be reduced. Thus, when heat-sealing the encapsulation part 31 of the packaging bag 3, the glue overflow between the transfer tab 11 and the encapsulation part 31 can be reduced, which is beneficial to improving the sealing performance between the transfer tab 11 and the encapsulation part 31.

[0074] In some embodiments, please refer to Figure 2 and Figure 6 , the transfer tab 11 includes an external connection section 113. Along the extension direction X of the transfer tab 11, the external connection section 113 is connected to one end of the adhesive section 112 departing from the internal connection section 111. The external connection section 113 is used for electrically connecting with a circuit board (not shown in the figure), so as to realize the electrical connection between the circuit board and the battery cell 2.

[0075] In some embodiments, a third groove 1203 is provided in a portion of the bonding member 12 bonded to the first surface 1121. Along the extension direction X of the transfer tab 11, the first groove 1201 and the third groove 1203 are oppositely arranged. The third groove 1203 is located at an edge of the bonding member 12 facing the external connection section 113, and the notch of the third groove 1203 faces the external connection section 113. With such an arrangement, when the bonding member 12 is compounded to the transfer tab 11, the risk of the bonding member 12 spreading along the extension direction X of the transfer tab 11 to the external connection section 113 can be reduced, thereby reducing the influence of the bonding member 12 on the soldering between the external connection section 113 and the circuit board and reducing the risk of poor soldering between the external connection section 113 and the circuit board. Additionally, when heat-sealing the encapsulation portion 31, the overflow glue between the first surface 1121 and the encapsulation portion 31 can be reduced, thereby improving the sealing performance between the first surface 1121 and the encapsulation portion 31.

[0076] In some embodiments, referring to Figure 4 and Figure 6 , a fourth groove 1204 is provided in a portion of the bonding member bonded to the second surface 1122. The fourth groove 1204 is provided at an edge of the bonding member 12 facing the external connection section 113, and the notch of the fourth groove 1204 faces the external connection section 113. With such an arrangement, when the bonding member 12 is compounded to the transfer tab 11, the risk of the bonding member 12 spreading along the extension direction X of the transfer tab 11 to the external connection section 113 can be reduced, thereby reducing the influence of the bonding member 12 on the soldering between the external connection section 113 and the circuit board and reducing the risk of poor soldering between the external connection section 113 and the circuit board. Additionally, when heat-sealing the encapsulation portion 31, the overflow glue between the second surface 1122 and the encapsulation portion 31 can be reduced, thereby improving the sealing performance between the second surface 1122 and the encapsulation portion 31.

[0077] In some embodiments, the internal connection section 111, the adhesive section 112, and the external connection section 113 are integrally formed. With such an arrangement, it is beneficial to improve the strength of the transfer tab 11 and simplify the processing procedure of the transfer tab 11.

[0078] In some embodiments, the shapes of the second groove 1202, the third groove 1203, and the fourth groove 1204 can be arc-shaped, semi-elliptical, rectangular, triangular, etc., and the present application does not limit this.

[0079] In some embodiments, along the thickness direction Z of the transfer tab 11, the first groove 1201 and the second groove 1202 are symmetric with each other.

[0080] In some embodiments, along the thickness direction Z of the transfer tab 11, the third groove 1203 and the fourth groove 1204 are symmetric with each other.

[0081] In some embodiments, referring toFigure 2 and Figure 6 Along the extension direction X of the transfer tab 11, the depth of the third groove 1203 is W2, and 0 < W2 ≤ 1 mm is satisfied. If W2 is too large, when heat-sealing the encapsulation part 31, there is a lack of the bonding member 12 material between the transfer tab 11 and the encapsulation part 31 at the third groove 1203, thus forming a depression, resulting in poor encapsulation between the transfer tab 11 and the encapsulation part 31 and affecting the sealing performance of the encapsulation part 31. Therefore, setting 0 < W2 can reduce the risk that the bonding member 12 spreads along the length direction of the transfer tab 11 to the external connection section 113 during the process of compounding the bonding member 12 to the transfer tab 11, which is beneficial to reducing the risk of false soldering when the external connection section 113 is soldered to the circuit board, thereby improving the connection stability between the external connection section 113 and the circuit board, and can reduce the glue overflow between the transfer tab 11 and the encapsulation part 31 when encapsulating the encapsulation part 31 of the packaging bag 3; setting W2 ≤ 1 mm can reduce the risk of forming a depression between the transfer tab 11 and the encapsulation part 31 at the third groove 1203 during the heat-sealing process of the encapsulation part 31, which is beneficial to improving the sealing performance of the encapsulation part 31.

[0082] It should be noted that the depth W2 of the above-mentioned third groove 1203 refers to the distance between the deepest concave part of the third groove 1203 and the second edge 1208 along the extension direction X of the transfer tab 11.

[0083] Furthermore, along the extension direction X of the transfer tab 11, the depth W2 of the third groove 1203 satisfies 0.1 mm ≤ W2 ≤ 0.8 mm. Setting 0.1 mm ≤ W2 can further reduce the risk that the bonding member 12 spreads along the length direction of the transfer tab 11 to the external connection section 113 during the process of compounding the bonding member 12 to the transfer tab 11, further reducing the risk of false soldering when the external connection section 113 is soldered to the circuit board, thereby improving the connection stability between the external connection section 113 and the circuit board, and can further reduce the glue overflow between the transfer tab 11 and the encapsulation part 31 when encapsulating the encapsulation part 31 of the packaging bag 3; setting W2 ≤ 0.8 mm is beneficial to further improving the sealing performance of the encapsulation part 31.

[0084] Further, along the extension direction X of the transfer tab 11, the depth W2 of the third groove 1203 satisfies 0.3 mm ≤ W2 ≤ 0.5 mm. Setting 0.3 mm ≤ W2 can further reduce the risk that the adhesive 12 spreads to the external connection section 113 along the length direction of the transfer tab 11 during the process of the adhesive 12 being compounded to the transfer tab 11, further reduce the risk of poor soldering when the external connection section 113 is soldered to the circuit board, and can further reduce the glue overflow between the transfer tab 11 and the encapsulation part 31 when encapsulating the encapsulation part 31; setting W2 ≤ 0.5 mm is beneficial to further improving the sealing performance of the encapsulation part 31.

[0085] In the embodiment of the present application, by providing the first groove 1201, when the adhesive 12 is compounded to the transfer tab 11, the risk that the adhesive 12 spreads along the extension direction X of the transfer tab 11 to the internal connection section 111 can be reduced. Furthermore, during the process of welding and fixing the internal connection section 111 to the internal tab 21 of the battery cell 2, the influence of the adhesive 12 on the welding between the internal connection section 111 and the internal tab 21 can be reduced, and the occurrence of poor soldering can be reduced, which is beneficial to improving the connection stability between the internal connection section 111 and the internal tab 21; in addition, when the tab assembly 1 and the battery cell 2 are placed in the packaging bag 3 and the encapsulation part 31 of the packaging bag 3 is heat-sealed, the glue overflow between the tab assembly 1 and the encapsulation part 31 can be reduced, which is beneficial to making the sealant at the adhesive 12 and the encapsulation part 31 melt more fully, thereby reducing microcracks or pores, improving the sealing performance between the encapsulation part 31 and the transfer tab 11, and further reducing the risk of electrolyte leakage in the packaging bag 3.

[0086] In a second aspect, the present application provides a secondary battery 100. Please refer to Figure 5 and Figure 6 , the secondary battery 100 includes a battery cell 2, a packaging bag 3 and the above-mentioned tab assembly 1. The battery cell 2 is received in the packaging bag 3. The battery cell 2 is provided with an internal tab 21. The internal connection section 111 is connected to the internal tab 21. The packaging bag 3 is provided with an encapsulation part 31. The adhesive section 112 passes through the encapsulation part 31, and the external connection section 113 at least partially protrudes from the encapsulation part 31 to facilitate the electrical connection between the external connection section 113 and the circuit board. Wherein, the encapsulation part 31 is provided with a molten layer (not shown in the figure), and the encapsulation part 31 is sealed by fusing with the adhesive 12 through the molten layer at high temperature.

[0087] It should be noted that the connection between the internal connection segment 111 and the internal tab 21 is achieved by welding, and the welding method can be any one of ultrasonic welding or laser welding. The welding between the internal connection segment 111 and the positive internal tab (mostly made of aluminum) can use ultrasonic welding, with an ultrasonic frequency of 20 kHz to 40 kHz, an amplitude of 30 μm to 60 μm, a pressure of 200 N to 500 N, a welding time of 0.2 s to 0.5 s, and a welding energy of 800 J to 1500 J; the welding between the internal connection segment 111 and the negative internal tab (mostly made of nickel or nickel-plated copper) can use laser welding, with a shielding gas of Ar (flow rate 10 L / min to 15 L / min), a laser wavelength of 1070 nm (fiber laser), a spot diameter of 0.2 mm to 0.5 mm, a power of 300 W to 800 W, and a welding speed of 50 mm / s to 200 mm / s.

[0088] In some embodiments, the battery cell 2 includes a cathode electrode sheet 24, a separator 23, and an anode electrode sheet 22. The cathode electrode sheet 24, the separator 23, and the anode electrode sheet 22 are alternately stacked in sequence, and the separator 23 is disposed between the cathode electrode sheet 24 and the anode electrode sheet 22. The above-mentioned internal tab 21 can be disposed on the cathode electrode sheet 24, can also be disposed on the anode electrode sheet 22, or internal tabs 21 can be simultaneously disposed on both the cathode electrode sheet 24 and the anode electrode sheet 22.

[0089] In some embodiments, the internal tab 21 is disposed at the end of the battery cell 2, and the internal tab 21 is bent and extended, and is generally U-shaped, so that the internal tab 21 forms a U-groove 211, wherein the orientation of the U-groove 211 is generally parallel to the thickness direction Z of the battery cell 2. The internal connection segment 111 includes a welding portion 1111 and a connection portion 1112. The welding portion 1111 is partially received in the U-groove 211, and the welding portion 1111 is fixedly welded to the internal tab 21. One end of the connection portion 1112 is connected to the end of the welding portion 1111 protruding from the U-groove 211, and the end of the connection portion 1112 away from the welding portion 1111 is connected to the adhesive segment 112, wherein the connection portion 1112 is substantially perpendicular to the welding portion 1111. Define the extending direction X of the welding portion 1111 as the first direction. By making the connection portion 1112 substantially perpendicular to the welding portion 1111, it is beneficial to reduce the size of the transfer tab 11 in the first direction, reduce the risk of the transfer tab 11 protruding from the battery cell 2 in the first direction, and is beneficial to reduce the size of the secondary battery 100 in the first direction.

[0090] It should be noted that the above-mentioned welding part 1111 and connecting part 1112 are formed by bending the internal connecting section 111. That is, after welding the welding part 1111 to the inner tab 21, the internal connecting section 111 needs to be bent, and then the battery cell 2 and the tab assembly 1 are placed into the packaging bag 3. Therefore, in this application, by providing the second groove 1202, when the bonding member 12 is compounded to the adhesive section 112, the risk of the bonding member 12 spreading to the bending part between the welding part 1111 and the connecting part 1112 can be reduced, thereby reducing the difficulty of bending the internal connecting section 111 due to the increased thickness of the transfer tab 11 at this bending part, and the stress generated due to the increased thickness at the bending part can be reduced.

[0091] In some embodiments, please refer to Figure 3 and Figure 6 , the welding part 1111 is provided with a first welding area 1113, and the first welding area 1113 is used for welding with the inner tab 21.

[0092] In some embodiments, please refer to Figure 6 and Figure 7 , Figure 7It is a schematic structural diagram of the tab assembly 1 after thermally sealing the tab assembly 1 and the encapsulation part 31. The bonding part 1205 has a third edge 1209 and a fourth edge 1210 that are oppositely arranged along the extension direction X of the transfer tab 11. One end of the third edge 1209 is butted against one end of the first edge 1207, and one end of the fourth edge 1210 is butted against the second edge 1208. Among them, the third edge 1209 is closer to the internal connection section 111 than the fourth edge 1210. Define a first tangent line F, and the first tangent line F extends along the width direction Y of the transfer tab 11. The first tangent line F is tangent to the position of the third edge 1209 farthest from the first edge 1207. Along the extension direction X of the transfer tab 11, the distance between the first edge 1207 and the second edge 1208 is W3, and the distance between the first tangent line F and the second edge 1208 is W4, and -0.2 mm ≤ W3 - W4 ≤ 0.5 mm is satisfied. If the value of W3 - W4 is too small, it is easy to cause the distance between the bonding member 12 and the first welding area 1113 to be too close, and even the bonding member 12 covers a part of the first welding area 1113, affecting the welding between the first welding area 1113 and the inner tab 21; if the value of W3 - W4 is too large, it is easy to cause a lack of bonding material between the transfer tab 11 and the encapsulation part 31, resulting in a large-area depression, and the sealing performance of the encapsulation part 31 is greatly reduced. Therefore, setting -0.2 mm ≤ W3 - W4 can reduce the risk of the bonding member 12 spreading to the first welding area 1113, which is beneficial to reducing the risk of false soldering between the inner tab 21 and the first welding area 1113, and can reduce the overflow of glue between the transfer tab 11 and the encapsulation part 31; setting W3 - W4 ≤ 0.5 mm can reduce the depression area between the transfer tab 11 and the encapsulation part 31 and improve the sealing performance of the encapsulation part 31.

[0093] Furthermore, -0.1 mm ≤ W3 - W4 ≤ 0.3 mm. Setting -0.1 mm ≤ W3 - W4 can further reduce the risk of the bonding member 12 spreading to the first welding area 1113, which is beneficial to further reducing the risk of false soldering between the inner tab 21 and the first welding area 1113, and can further reduce the overflow of glue between the transfer tab 11 and the encapsulation part 31; setting W3 - W4 ≤ 0.3 mm can further reduce the depression area between the transfer tab 11 and the encapsulation part 31 and improve the sealing performance of the encapsulation part 31.

[0094] Furthermore, 0 ≤ W3 - W4 ≤ 0.3 mm. Setting 0 ≤ W3 - W4 can further reduce the risk of the bonding member 12 spreading to the first welding area 1113, which is beneficial to further reducing the risk of false soldering between the inner tab 21 and the first welding area 1113, and can further reduce the overflow of glue between the transfer tab 11 and the encapsulation part 31.

[0095] It should be noted that W3 - W4 < 0, which means that along the extension direction X of the transition tab 11, the first tangent line F is located on the side of the first edge 1207 close to the internal connection section 111, that is, the edge of the bonding member 12 on the bonding section 112 protrudes from the first edge 1207. W3 - W4 > 0 means that the first tangent line F is located on the side of the first edge 1207 close to the bonding section 112, that is, the edge of the bonding member 12 on the bonding section 112 does not protrude from the first edge 1207.

[0096] In some embodiments, the average thickness of the bonding portion 1205 within 0.1 mm of the third edge 1209 is less than the average thickness of the protruding portion 1206. This is because at least part of the bonding portion 1205 within 0.1 mm of the third edge 1209 is formed by the overflow of the bonding member 12 caused by the extrusion of the bonding member 12 during the heat - sealing process of the packaging bag 3, and the thickness of the bonding member 12 at this position is less than the thickness of the protruding portion 1206. It should be noted that along the width direction of the bonding member 12, that is, along the extension direction X of the transition tab 11, the bonding member 12 is further divided into an inner unsealed area close to the internal connection section 111, an outer unsealed area close to the external connection section 113, and an effective sealing area located between the inner unsealed area and the outer unsealed area. The effective sealing area is the part where the packaging bag 3 and the bonding member 12 are actually hot - pressed and fused. The average thickness of the bonding portion 1205 within 0.1 mm of the above - mentioned third edge 1209 refers to the result of taking the average value of the thicknesses measured at three positions of the bonding portion 1205 within 0.1 mm of the third edge 1209 located in the inner unsealed area. The average thickness of the above - mentioned protruding portion 1206 refers to the result of taking the average value of the thicknesses measured at three positions of the protruding portion 1206 located in the inner unsealed area.

[0097] In some embodiments, please refer to Figure 2 and Figure 6 , along the extension direction X of the transition tab 11, the minimum distance between one edge of the first welding area 1113 close to the bonding section 112 and the edge of the bonding member 12 facing the first welding area 1113 is W5, and 0.2 mm ≤ W5 ≤ 1 mm. If the value of W5 is too small, the bonding member 12 is likely to affect the welding between the first welding area 1113 and the inner tab 21, and the risk of false soldering is relatively high, resulting in a decrease in the welding tensile force between the first welding area 1113 and the inner tab 21. If the value of W5 is too large, on the premise that the size of the first welding area 1113 remains unchanged, the risk of false soldering at the root of the first welding area 1113 and the inner tab 21 increases, and it is also likely to cause a decrease in the welding tensile force. Moreover, if W5 is too large, it is easy to cause a loss of the volume energy density of the battery cell 2. Therefore, setting 0.2 mm ≤ W5 ≤ 1 mm can reduce the risk of false soldering between the first welding area 1113 and the inner tab 21, is beneficial to improving the welding tensile force between the first welding area 1113 and the inner tab 21, and improving the volume energy density of the battery cell 2.

[0098] Further, 0.4 mm ≤ W5 ≤ 0.8 mm. By setting 0.4 mm ≤ W5 ≤ 0.8 mm, the risk of false soldering formed between the first welding area 1113 and the inner tab 21 can be further reduced, which is beneficial to further improving the welding tensile force between the first welding area 1113 and the inner tab 21.

[0099] In some embodiments, the secondary battery 100 includes a circuit board (not shown in the figure), and the circuit board is fixedly welded to the external connection section 113. The circuit board can control the current and voltage input and output by the battery cell 2. Among them, the welding process between the external connection section 113 and the circuit board can use selective wave soldering, the temperature of the solder bath is 250°C to 270°C, the contact time is 3 s to 5 s, and it is carried out in a nitrogen protection atmosphere with O2 < 100 ppm.

[0100] Please refer to Figure 6 and Figure 7 , define a second tangent line H. The second tangent line H extends along the width direction Y of the transfer tab 11, and the second tangent line H is tangent to the position of the fourth edge 1210 farthest from the second edge 1208. Along the extension direction X of the transfer tab 11, the distance between the second tangent line H and the first edge 1207 is W6, and -0.8 mm ≤ W3 - W6 ≤ 0.8 mm. If the value of W3 - W6 is too small, it means that the distance between the bonding member 12 and the welding position between the external connection section 113 and the circuit board is too small, which easily increases the risk of false soldering between the external connection section 113 and the circuit board; if the value of W3 - W6 is too large, it easily causes the area of the depression formed by the bonding member 12 between the transfer tab 11 and the encapsulation part 31 to be too large, resulting in a decrease in the sealing performance. Therefore, setting -0.8 mm ≤ W3 - W6 is beneficial to reducing the risk of false soldering between the external connection section 113 and the circuit board, thereby improving the welding tensile force between the external connection section 113 and the circuit board; setting W3 - W6 ≤ 0.8 mm can reduce the area of the depression formed by the bonding member 12 between the transfer tab 11 and the encapsulation part 31, which is beneficial to improving the encapsulation strength.

[0101] Further, -0.5 mm ≤ W3 - W6 ≤ 0.5 mm. Setting -0.5 mm ≤ W3 - W6 is beneficial to further reducing the risk of false soldering between the external connection section 113 and the circuit board, thereby further improving the welding tensile force between the external connection section 113 and the circuit board; setting W3 - W6 ≤ 0.5 mm can further reduce the area of the depression formed by the bonding member 12 between the transfer tab 11 and the encapsulation part 31, which is beneficial to further improving the encapsulation strength.

[0102] Further, -0.3 mm ≤ W3 - W6 ≤ 0.3 mm. Setting -0.3 mm ≤ W3 - W6 is beneficial to further reduce the risk of solder joint voids between the external connection section 113 and the circuit board, thereby further enhancing the soldering tensile force between the external connection section 113 and the circuit board; setting W3 - W6 ≤ 0.3 mm can further reduce the area where the adhesive 12 between the transfer tab 11 and the encapsulation part 31 forms a depression, which is beneficial to further enhancing the encapsulation strength.

[0103] Further, 0 ≤ W3 - W6 ≤ 0.3 mm. Setting 0 ≤ W3 - W6 is beneficial to further reduce the risk of solder joint voids between the external connection section 113 and the circuit board, thereby further enhancing the soldering tensile force between the external connection section 113 and the circuit board.

[0104] It should be noted that when W3 - W6 is less than 0, it means that along the extension direction X of the transfer tab 11, the second tangent line H is located on the side of the second edge 1208 close to the external connection section 113, that is, the edge of the adhesive 12 on the adhesive section 112 protrudes from the second edge 1208. When W3 - W6 is greater than 0, it means that the second tangent line H is located on the side of the second edge 1208 close to the adhesive section 112, that is, the edge of the adhesive 12 on the adhesive section 112 does not protrude from the second edge 1208.

[0105] In some embodiments, the average thickness of the adhesive part 1205 within 0.1 mm of the fourth edge 1210 is less than the average thickness of the protruding part 1206. This is because at least part of the adhesive part 1205 within 0.1 mm of the fourth edge 1210 is formed by the overflow of the adhesive 12 caused by the extrusion of the adhesive 12 during the heat sealing process of the packaging bag 3, and the thickness of the adhesive 12 at this position is less than the thickness of the protruding part 1206. It should be noted that the average thickness of the adhesive part 1205 within 0.1 mm of the fourth edge 1210 mentioned above refers to the result of taking the average value after measuring the thickness at three positions of the adhesive part 1205 within 0.1 mm of the fourth edge 1210 in the outer unsealed area. The average thickness of the protruding part 1206 mentioned above refers to the result of taking the average value after measuring the thickness at three positions of the protruding part 1206 in the outer unsealed area.

[0106] In a third aspect, the present application provides an electronic device, which includes the secondary battery 100 described above. For the specific structure and functions of the secondary battery 100, please refer to the above embodiments and will not be elaborated herein one by one.

[0107] In a fourth aspect, the present application provides a method for manufacturing the secondary battery 100 described above. Please refer to Figure 8 and Figure 9 , Figure 9 is a schematic structural diagram when the adhesive 12 is not compounded to the transfer tab 11. The method includes:

[0108] Step S01: Provide a battery cell 2, a packaging film, a transfer tab 11 and an adhesive member 12. The battery cell 2 is provided with an internal tab 21. The packaging film is provided with a pit for accommodating the battery cell 2, and the edges of the packaging film are provided with a first sealant and a second sealant. The transfer tab 11 includes an internal connection section 111, an adhesive section 112 and an external connection section 113. Along the extension direction X of the transfer tab 11, the adhesive section 112 is disposed between the internal connection section 111 and the external connection section 113;

[0109] Step S02: Cut the edges of the adhesive member 12 in the width direction of the adhesive member 12, so as to form an avoidance groove 1211 at the cut, and the notch of the avoidance groove 1211 faces the edge in the width direction of the adhesive member 12;

[0110] Step S03: Thermally bond the adhesive member 12 to the adhesive section 112 to form the above-mentioned tab assembly 1. Wherein, the adhesive member 12 forms a first groove 1201 at the avoidance groove 1211, and the notch of the first groove 1201 faces the internal connection section 111;

[0111] Step S04: Weld and fix the internal connection section 111 to the internal tab 21;

[0112] Step S05: Place the battery cell 2 in the pit. Wherein, when observing along the thickness direction of the adhesive member 12, the orthographic projection of the adhesive member 12 bonded to the adhesive section 112 at least partially overlaps with the orthographic projection of the first sealant or the second sealant, and the transfer tab 11 at least partially protrudes from the edge of the packaging film;

[0113] Step S06: Fold the packaging film so that the first sealant and the second sealant overlap each other. Wherein, the transfer tab 11 extends out from between the first sealant and the second sealant, and the adhesive member 12 is located between the first sealant and the second sealant;

[0114] Step S07: Thermally melt the first sealant, the second sealant and the adhesive member 12 to form a secondary battery 100.

[0115] In this embodiment, by cutting the edges of the adhesive member 12 in the width direction Y of the adhesive member 12, an avoidance groove 1211 is formed at the cut, and the notch of the avoidance groove 1211 faces the edge in the width direction Y of the adhesive member 12. On the one hand, during the process of thermally bonding the adhesive member 12 to the adhesive section 112, the risk of the adhesive member 12 spreading to the internal connection section 111 can be reduced, and further the risk of poor welding between the internal connection section 111 and the internal tab 21 can be reduced; on the other hand, during the process of thermally melting the first sealant, the second sealant and the adhesive member 12, the formation of overflow glue can be reduced.

[0116] In some embodiments, please refer to Figure 3 、Figure 6 and Figure 9 , along the extension direction X of the transfer tab 11, the depth of the avoidance groove 1211 is W7, where 0.4 mm < W7 ≤ 1.5 mm. It should be noted that during the process of heat-fusing the bonding member 12 to the transfer tab 11, the bonding member 12 gradually spreads towards the internal connection section 111, resulting in the partial area of the avoidance groove 1211 being gradually filled by the bonding member 12, thereby forming the above-mentioned first groove 1201; during the process of heat-fusing the first sealant, the second sealant and the bonding member 12, the bonding member 12 further spreads towards the internal connection section 111, resulting in at least part of the area of the first groove 1201 being gradually filled by the bonding member 12. At this time, the third edge 1209 of the part of the bonding member 12 bonded to the adhesive section 112 can protrude towards the internal connection section 111 beyond the first edge 1207, or can be recessed towards the inside of the bonding member 12 away from the internal connection section 111. If the value of W7 is too large, during the process of heat-fusing the first sealant, the second sealant and the bonding member 12, there is a lack of the bonding member 12 at the first groove 1201 between the transfer tab 11 and the encapsulation part 31, resulting in an excessive area of the depression, leading to poor encapsulation between the transfer tab 11 and the encapsulation part 31 of the packaging bag 3 and affecting the sealing performance of the encapsulation part 31; if the value of W7 is too small, when heat-fusing and bonding the bonding member 12 to the adhesive section 112, it is easy for the bonding member 12 to spread to the internal connection section 111, thereby affecting the welding between the internal connection section 111 and the inner tab 21, resulting in a situation of poor welding between the two. During the process of heat-fusing the first sealant, the second sealant and the bonding member 12, it is easy to form glue overflow. Therefore, setting 0.4 mm < W7 can reduce the risk of the bonding member 12 spreading to the internal connection section 111 during the process of bonding the bonding member 12 to the transfer tab 11, which is beneficial to reducing the risk of poor welding between the internal connection section 111 and the inner tab 21, and can reduce glue overflow when heat-fusing and bonding the bonding member 12 to the adhesive section 112; setting W7 ≤ 1.5 mm can reduce the risk of forming a depression at the first groove 1201 between the transfer tab 11 and the encapsulation part 31 during the process of heat-fusing and bonding the bonding member 12 to the adhesive section 112, which is beneficial to improving the sealing performance of the encapsulation part 31.

[0117] Further, 0.7 mm ≤ W7 ≤ 1.2 mm. By setting 0.7 mm ≤ W7, the risk of the bonding member 12 spreading to the internal connection section 111 during the process of bonding the bonding member 12 to the transfer tab 11 can be further reduced, which is beneficial to further reducing the risk of poor soldering between the internal connection section 111 and the inner tab 21. Moreover, when the bonding member 12 is hot-melt bonded to the adhesive section 112, the risk of glue overflow can be further reduced. By setting W7 ≤ 1.2 mm, during the process of hot-melt bonding the bonding member 12 to the adhesive section 112, the risk of forming a depression at the first groove 1201 between the transfer tab 11 and the encapsulation part 31 can be further reduced, which is beneficial to further improving the sealing performance of the encapsulation part 31.

[0118] In some embodiments, along the width direction Y of the transfer tab 11, the size of the adhesive section 112 is L1, and along the length direction of the bonding member 12, the size of the avoidance groove 1211 is L3, where 0.8 ≤ L3 / L1 ≤ 1.2. If the ratio between L3 and L1 is too small, when the bonding member 12 is hot-melt bonded to the adhesive section 112, the bonding member 12 is likely to spread to the internal connection section 111, thereby affecting the soldering between the internal connection section 111 and the inner tab 21. Moreover, when the first sealant, the second sealant, and the bonding member 12 are hot-melted, the bonding member 12 further spreads to the internal connection section 111, thus easily forming glue overflow. If the ratio between L3 and L1 is too large, it is likely to result in insufficient bonding area between the bonding member 12 and the adhesive section 112, affecting the stability of the connection between the bonding member 12 and the adhesive section 112. Moreover, when the first sealant, the second sealant, and the bonding member 12 are hot-melted, it is likely to cause poor encapsulation between the transfer tab 11 and the encapsulation part 31, with insufficient sealing between the transfer tab 11 and the encapsulation part 31 and a risk of liquid leakage. Therefore, by setting 0.8 ≤ L3 / L1 ≤ 1.2, the glue overflow between the transfer tab 11 and the encapsulation part 31 can be reduced, taking into account the risk of reducing poor encapsulation and improving the sealing performance between the transfer tab 11 and the encapsulation part 31.

[0119] Further, 0.9 ≤ L3 / L1 ≤ 1.1. By setting 0.9 ≤ L3 / L1, the glue overflow between the transfer tab 11 and the encapsulation part 31 can be further reduced. By setting L3 / L1 ≤ 1.1, the risk of poor encapsulation can be further reduced, and the sealing performance between the transfer tab 11 and the encapsulation part 31 can be improved.

[0120] To better understand the concept of this application, experimental verification is carried out below.

[0121] The preparation of the secondary battery in Example 1 is as follows:

[0122] <Preparation of the cathode electrode sheet>

[0123] Mix the cathode material lithium cobaltate, the first binder polyvinylidene fluoride, and the first conductive agent conductive carbon black in a mass ratio of 95:3:2, add N-methylpyrrolidone (NMP) as a solvent, and stir evenly with a vacuum mixer to obtain a slurry of the first material layer with a solid content of 75 wt%. Use aluminum foil with a thickness of 10 μm as the cathode current collector, and coat the slurry of the first material layer on the surface of one side of the aluminum foil. The single-sided coating weight of the first material layer is 260 mg / 1540 mm 2 . Then repeat the above coating step on the surface of the other side of the aluminum foil, dry it at 90 °C, and use a pressure of 40 t - 80 t at 25 °C to compact the cathode electrode sheet to reach the set thickness specification of 90 μm, obtaining a cathode electrode sheet with a double-sided coating of the first material layer. Use aluminum foil with a thickness of 20 μm as the cathode current collector, coat the slurry of the first material layer on one surface of the 20-μm aluminum foil, dry it, and compact it to obtain a cathode electrode sheet with a single-sided coating of the first material layer. Then, after cutting, obtain a cathode electrode sheet with a specification of 60 mm × 110 mm for use. Among them, the cathode electrode sheet is provided with a first tab.

[0124] <Preparation of Anode Electrode Sheet>

[0125] Mix the anode material artificial graphite, silicon carbide compound, the second binder styrene-butadiene rubber (SBR), and carboxymethyl cellulose (CMC) in a mass ratio of 87.7:10:1:1.3, then add deionized water as a solvent, and formulate it into a slurry with a solid content of 70 wt%. Stir evenly with a vacuum mixer to obtain a slurry of the second material layer. Coat the slurry of the second material layer on one surface of an anode current collector with a thickness of 6 μm. The single-sided coating weight of the second material layer is 140 mg / 1540 mm 2 . Then repeat the above steps on the other surface of the copper foil, dry it at 120 °C and then cold press it to obtain an anode electrode sheet with a double-sided coating of the second material layer. Then, after cutting, obtain an anode electrode sheet with a specification of 64 mm × 114 mm for use. Among them, the anode electrode sheet is provided with a second tab.

[0126] <Preparation of Tab Assembly>

[0127] Cut the first tab glue so that a relief groove is formed at each of the two edges in the width direction of the first tab glue. Set the first tab glue on one surface of the metal strip. Among them, the first tab glue and the metal strip are arranged in a substantially cross shape; set the second tab glue on the other surface of the metal strip. A relief groove is formed at each of the two edges in the width direction of the second tab glue. The second tab glue and the metal strip are arranged in a substantially cross shape, and the first tab glue and the second tab glue overlap each other along the thickness direction of the metal strip. The relief grooves provided on the first tab glue and the second tab glue overlap each other along the thickness direction of the metal strip; hot press the first tab glue and the second tab glue (hot press pressure 0.1 MPa, hot press temperature 150 °C, hot press time 1.5 s) to obtain a tab assembly. Among them, the first tab glue and the second tab glue form a bonding member, and the metal strip forms a transfer tab. The relief groove on the first tab glue forms a first groove and a third groove, and the relief groove provided on the second tab glue forms a second groove and a fourth groove. The length and depth of the first groove are the same as those of the second groove, and the length and depth of the third groove are the same as those of the fourth groove.

[0128] <Preparation of electrolyte>

[0129] In an argon atmosphere glove box with a water content of less than 10 ppm, uniformly mix ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) of carbonate compounds in a mass ratio of 10:30:60 to obtain a base solvent, and add lithium salt LiPF6 and stir evenly to obtain an electrolyte. Among them, based on the total mass of the electrolyte, the mass percentage content of lithium salt LiPF6 is 12.5%, and the balance is the base solvent.

[0130] <Separator>

[0131] Use a polyethylene porous polymer film with a thickness of 8 μm as the separator.

[0132] <Preparation of secondary battery>

[0133] Stack the cathode electrode sheet, separator, and anode electrode sheet alternately in sequence to form a laminated structure battery cell, with the separator placed between the cathode electrode sheet and the anode electrode sheet to play an isolation role. Among them, two single-sided cathode electrode sheets serve as the two outermost electrode sheets of the laminated battery cell. Stack the first sub-tab ears on the cathode electrode sheet together along the thickness direction of the first sub-tab ear to form a first inner tab ear, and weld a transfer tab ear to the first inner tab ear. Among them, the avoidance groove on the bonding part faces the first inner tab ear; stack the second sub-tab ears on the anode electrode sheet together along the thickness direction of the second sub-tab ear to form a second inner tab ear, and weld another transfer tab ear with the opposite polarity to the second inner tab ear. Among them, the avoidance groove on the bonding part faces the second inner tab ear. Among them, ultrasonic welding is used for the welding between the transfer tab ear and the first inner tab ear, with an ultrasonic frequency of 30 kHz, an amplitude of 45 μm, a pressure of 300 N, a welding time of 0.5 s, and a welding energy of 1200 J; laser welding is used for the welding between the transfer tab ear and the second inner tab ear, with a shielding gas of Ar (flow rate 15 L / min), a laser wavelength of 1070 nm (fiber laser), a spot diameter of 0.4 mm, a power of 500 W, and a welding speed of 150 mm / s. The weld width formed by welding the transfer tab ear to the first inner tab ear and the second inner tab ear is 0.6 mm, and the number of weld spots is 8. Place the above laminated battery cell welded with the tab ear assembly into an aluminum-plastic film packaging bag, remove moisture at 80 °C, inject the prepared electrolyte, and obtain a secondary battery through vacuum packaging, standing, formation, and shaping processes. Among them, the upper limit voltage of formation is 4.53 V, the formation temperature is 85 °C, and the formation time is 45 min to 60 min. Among them, the heat sealing pressure between the packaging bag and the bonding part is 0.5 MPa, the heat sealing temperature is 200 °C, the heat sealing time is 3 s, and the cooling time is 3 s.

[0134] Different from Example 1, in Comparative Example 1, the first tab ear adhesive does not have an avoidance groove, that is, there is no groove on the bonding part;

[0135] Different from Example 1, in Comparative Example 2, the edge in the width direction of the bonding part on the adhesive section protrudes beyond the edge of the bonding part outside the adhesive section.

[0136] Different from Example 1, in Example 2, only one edge in the width direction of the first tab ear adhesive has an avoidance groove, that is, the bonding part in Example 2 only has a first groove;

[0137] Different from Example 1, in Example 3, one edge in the width direction of the first tab ear adhesive and the second tab ear adhesive has an avoidance groove, that is, the bonding part in Example 3 has a first groove and a second groove;

[0138] Different from Example 1, relief grooves are provided on both sides of the first tab glue in Example 4, and relief grooves are provided on only one side of the second tab glue. That is to say, the bonding member in Example 4 is provided with a first groove, a second groove, and a third groove;

[0139] For the specific differences between the parameters of Examples 5 to 43 and those of Example 1, please refer to Table 1 and Table 2. Among them, the sizes of the first groove and the second groove are the same, and the sizes of the third groove and the fourth groove are the same. Except for the differences listed in Table 1 and Table 2, all other parameters of Examples 5 to 43 are the same as those of Example 1.

[0140] Among them, the outer connection section of the transfer tab in each example is also connected to the circuit board. Among them, the welding method between the transfer tab and the circuit board connection terminal is selective wave soldering. In a nitrogen protection atmosphere with O2 < 100 ppm, the solder bath temperature is 270 °C, the contact time is 5 s, the solder print width is 1 mm, and the number of solder joints is 8.

[0141] The test method is as follows:

[0142] Welding tensile strength test method between the transfer tab and the inner tab: Take the welded transfer tab and inner tab, fix the transfer tab on the upper fixture of the horizontal tensile tester, and fix the inner tab on the lower fixture of the horizontal tensile tester, ensuring that the tensile direction is perpendicular to the welding surface (angle deviation ≤ 2°), set the tensile value to 15 N, the duration to 30 s, start the equipment, and observe whether the transfer tab and the inner tab are separated after the test.

[0143] Judgment criteria for the welding tensile strength test between the transfer tab and the inner tab: If peeling occurs at the welding interface or the solder joint breaks, it is regarded as unqualified; if neither the base material (non-welding interface) nor the welding interface shows fracture or peeling, it is regarded as qualified; if the base material (non-welding interface) fractures and the welding interface does not show peeling or fracture, it is regarded as qualified. The welding tensile strength between the transfer tab and the inner tab is recorded as the first welding tensile strength. For each group of examples or comparative examples, 20 battery cells are tested, and the number of battery cells with qualified first welding tensile strength test is X1, and the passing rate of the first welding tensile strength test is recorded as X1 / 20.

[0144] Welding tensile strength test method between the transfer tab and the circuit board connection terminal: Take the welded transfer tab and the circuit board connection terminal, fix the transfer tab on the upper fixture of the horizontal tensile tester, and fix the circuit board connection terminal on the lower fixture of the horizontal tensile tester, ensuring that the tensile direction is perpendicular to the welding surface (angle deviation ≤ 2°), set the tensile value to 20 N, the duration to 30 s, start the equipment, and observe whether the transfer tab and the circuit board connection terminal are separated after the test.

[0145] The passing judgment criteria for the welding tensile strength test between the transfer tab and the circuit board connection terminal: If peeling occurs at the welding interface or the solder joint breaks, it is regarded as unqualified; if neither the base material (non-welding interface) nor the welding interface shows fracture or peeling, it is regarded as qualified; if the base material (non-welding interface) fractures and the welding interface does not show peeling or fracture, it is regarded as qualified. The welding tensile strength between the transfer tab and the circuit board connection terminal is recorded as the second welding tensile strength. For each group of examples or comparative examples, 20 battery cells are tested. The number of battery cells with qualified second welding tensile strength test is X2, and the passing rate of the second welding tensile strength test is recorded as X2 / 20. Secondary battery encapsulation strength test (red ink test): Immerse the battery cell in red ink for 12 h. Take out the battery cell from the red ink, corrode the nylon layer in the encapsulation film at the encapsulation part with aqua regia, and corrode the metal layer in the encapsulation film at the encapsulation part with hydrochloric acid solution to expose the polymer layer in the encapsulation film, then rinse with clean water and use an optical microscope to observe whether the polymer layer in the encapsulation film at the encapsulation part is penetrated by red ink. If it is penetrated by red ink, it indicates that there is a liquid leakage channel in the polymer layer of the encapsulation film at the top sealing part, and the test is judged as not passing; if it is not penetrated by red ink, the test is judged as passing. For each group of examples and comparative examples, 20 battery cells are tested. The number of battery cells passing the test is X3, and the passing rate of the test is X3 / 20.

[0146] In Table 1 and Table 2 below, L1 represents the size of the adhesive section of the bonding member along the width direction of the transfer tab; L2 represents the size of the first groove along the width direction of the transfer tab; W1 is the depth of the first groove along the extension direction of the transfer tab; W2 represents the depth of the third groove along the extension direction of the transfer tab; W3 represents the distance between the first edge and the second edge along the extension direction of the transfer tab; W4 represents the distance between the first tangent and the second edge along the extension direction of the transfer tab; W5 represents the minimum distance between one edge of the first welding area close to the adhesive section and the edge of the bonding member facing the first welding area along the extension direction of the transfer tab; W6 represents the distance between the second tangent and the first edge along the extension direction of the transfer tab. Among them, the unit of each of the above dimensions is mm.

[0147] Table 1:

[0148]

[0149]

[0150]

[0151]

[0152] In Table 1, "\\" represents the absence of this parameter. In Comparative Example 1, W1 being "-0.1" means that on the side facing the inner connection section, the edge of the bonding member in the width direction of the bonding member on the adhesive section protrudes 0.1 mm beyond the edge of the adhesive section; W2 being "-0.1" means that on the side facing the outer connection section, the edge of the bonding member in the width direction of the bonding member on the adhesive section protrudes 0.1 mm beyond the edge of the adhesive section.

[0153] From the experimental data of Comparative Example 1, Comparative Example 2, and Examples 1 to 23 in Table 1, it can be seen that setting grooves on the bonding member in the tab assembly can improve the welding stability between the transfer tab and the inner tab and / or the circuit board connection terminal. This is because setting the grooves can reduce the risk of the bonding member spreading along the extension direction of the transfer tab to the internal connection section and / or the external connection section. Thus, during the process of welding and fixing the internal connection section to the inner tab of the battery cell, or during the process of welding and fixing the external connection section to the circuit board connection terminal, it is possible to reduce the influence of the bonding member on the welding and reduce the occurrence of false soldering, thereby improving the welding stability.

[0154] From the experimental data of Examples 1 to 4 in Table 1, it can be seen that setting the first groove and the second groove simultaneously on the bonding member can improve the passing rate of the first welding tensile strength test; setting the third groove and the fourth groove simultaneously can improve the passing rate of the second welding tensile strength test.

[0155] From Examples 1 and Examples 5 to 10 in Table 1, it can be seen that when L2 / L1 < 0.9, the length of the first groove is too small, and the risk of interference between the bonding member and the weld mark between the internal connection section and the inner tab is relatively high, resulting in a low passing rate of the first welding tensile strength test; when L2 / L1 > 1.1, the length of the first groove is too large, which affects the encapsulation strength, resulting in a low passing rate of the encapsulation strength test. Therefore, considering the influence of the length of the first groove on the first welding tensile strength and the encapsulation strength comprehensively, 0.9 ≤ L2 / L1 ≤ 1.1 is selected. Further preferably, 0.95 ≤ L2 / L1 ≤ 1.05.

[0156] From Examples 1 and Examples 11 to 16 in Table 1, it can be seen that as the depth W1 of the first groove increases, the passing rate of the first welding tensile strength test increases. This is because after the depth of the first groove increases, the risk of interference between the bonding member and the weld mark between the internal connection section and the inner tab decreases. However, when W1 is too large, it affects the encapsulation strength, resulting in a low passing rate of the encapsulation strength test. To balance the stability of the first welding tensile strength and the encapsulation strength, 0 < W1 ≤ 0.8 mm is selected; preferably, 0 < W1 ≤ 0.5 mm; further preferably, 0 < W1 ≤ 0.5 mm; further preferably, 0 < W1 ≤ 0.3 mm; further preferably, 0.1 mm ≤ W1 ≤ 0.3 mm.

[0157] From the experimental data of Example 1 and Examples 17 to 23 in Table 1, it can be seen that as the depth W2 of the third groove increases, the passing rate of the second welding tensile test increases. This is because after the depth of the second groove increases, the risk of interference between the bonding part and the solder prints between the external connection section and the circuit board connection terminal decreases. However, when W2 is too large, it affects the packaging strength, resulting in a low passing rate of the packaging strength test. To balance the stability of the second welding tensile force and the packaging strength, 0 < W2 ≤ 1 mm is selected; preferably 0.1 mm ≤ W2 ≤ 0.8 mm; more preferably 0.3 mm ≤ W2 ≤ 0.5 mm.

[0158] Table 2:

[0159]

[0160]

[0161] From the experimental data of Example 1 and Examples 24 to 30 in Table 2, it can be seen that when W3 - W4 < -0.2 mm, the passing rate of the first welding tensile test is low. This is because the distance between the third edge of the bonding part and the solder prints of the internal connection section and the internal tab is too small, resulting in a high risk of interference between the bonding part and the solder prints, thus affecting the stability of the solder prints of the internal connection section and the internal tab. When W3 - W4 > 0.5 mm, the passing rate of the packaging strength test is low. This is because the third edge of the bonding part is at a relatively large distance from the internal connection section compared to the first edge, resulting in a reduction in the effective area of the bonding part for bonding, thus affecting the stability of the packaging strength. To balance the first welding tensile force and the packaging strength, -0.2 mm ≤ W3 - W4 ≤ 0.5 mm is selected; preferably -0.1 mm ≤ W3 - W4 ≤ 0.3 mm; more preferably 0 ≤ W3 - W4 ≤ 0.3 mm.

[0162] From the experimental data of Example 1 and Examples 31 to 39 in Table 2, it can be seen that when W3 - W6 < -0.8 mm, the passing rate of the second welding tensile test is low. This is because the distance between the fourth edge of the bonding part and the solder prints of the external connection section and the circuit board connection terminal is too small, resulting in a high risk of interference between the bonding part and the solder prints, thus affecting the stability of the solder prints of the external connection section and the circuit board connection terminal. When W3 - W6 > 0.8 mm, the passing rate of the packaging strength test is low. This is because the fourth edge of the bonding part is at a relatively large distance from the external connection section compared to the second edge, resulting in a reduction in the effective area of the bonding part for bonding, thus affecting the stability of the packaging strength. To balance the second welding tensile force and the packaging strength, -0.8 mm ≤ W3 - W6 ≤ 0.8 mm is selected; preferably -0.5 mm ≤ W3 - W6 ≤ 0.5 mm; more preferably -0.3 mm ≤ W3 - W6 ≤ 0.3 mm; more preferably 0 ≤ W3 - W6 ≤ 0.3 mm.

[0163] As can be seen from the experimental data of Example 1 and Examples 40 to 43 in Table 2, when W5 < 0.2 mm, the passing rate of the first welding tensile test is relatively low. This is because the welding mark distance between the internal connection section and the inner tab to the bonding part is relatively close, resulting in a relatively high risk of interference between the bonding part and the welding mark, thus affecting the stability of the first welding tensile force. When W5 > 1 mm, the passing rate of the first welding tensile test is also relatively low. This is because when the welding mark area of the internal connection section and the inner tab remains unchanged, if W5 is too large, it will lead to a relatively high risk of interference between the welding mark and the root of the inner tab, also affecting the stability of the first welding tensile force. Therefore, 0.2 mm ≤ W5 ≤ 1 mm is selected.

[0164] The above are only the embodiments of the present application, and do not limit the patent scope of the present application accordingly. Any equivalent structure or equivalent process transformation made by using the content of the specification and drawings of the present application, or directly or indirectly applied in other related technical fields, shall be similarly included in the patent protection scope of the present application.

Claims

1. A tab assembly, comprising a transfer tab and a bonding member, wherein along the extension direction of the transfer tab, the transfer tab comprises an internal connection section and an adhesive section, one end of the adhesive section is connected to the internal connection section, the internal connection section is used to be electrically connected to a battery cell, the bonding member wraps the adhesive section and is bonded and fixed to the adhesive section, characterized in that: A first groove is provided at a portion of the bonding member bonded to the adhesive section. The first groove is located at an edge of the bonding member facing the internal connecting section, and a notch of the first groove faces the internal connecting section.

2. The tab assembly according to claim 1, characterized in that: Along the thickness direction of the adapter tab, the adhesive section includes a first surface and a second surface that are arranged opposite to each other; part of the adhesive is bonded to the first surface, and part of the adhesive is bonded to the second surface; the first groove is arranged at the part where the adhesive is bonded to the first surface, and the part where the adhesive is bonded to the second surface is provided with a second groove, and the second groove is located at an edge of the adhesive facing the internal connecting section, and the notch of the second groove faces the internal connecting section.

3. The tab assembly according to claim 1, characterized in that: The transfer tab comprises an external connection section, and along the extension direction of the transfer tab, the external connection section is connected to an end of the adhesive section away from the internal connection section; The adhesive is provided with a third groove, and along the thickness direction of the adapter electrode, the adhesive section includes a first surface and a second surface arranged opposite to each other, a portion of the adhesive is bonded to the first surface, the first groove and the third groove are both arranged at the portion where the adhesive is bonded to the first surface, the first groove and the third groove are arranged opposite to each other along the extension direction of the adapter electrode, the third groove is located at an edge of the adhesive facing the external connection section, and the notch of the third groove faces the external connection section.

4. The tab assembly according to claim 3, characterized in that: Part of the adhesive is bonded to the second surface, and the part of the adhesive bonded to the second surface is provided with a fourth groove, the fourth groove is located at an edge of the adhesive facing the external connecting section, and the notch of the fourth groove faces the external connecting section.

5. The tab assembly according to claim 1, characterized in that: Along the width direction of the switching tab, the size of the adhesive section is L1, the size of the first groove is L2, and 0.9≤L2 / L1≤1.

1.

6. The tab assembly according to claim 5, characterized in that: 0.95≤L2 / L1≤1.

05.

7. The tab assembly according to claim 1, characterized in that: Along the extending direction of the switching tab, the depth of the first groove is W1, 0<W1≤0.8mm.

8. The tab assembly according to claim 7, characterized in that: 0<W1≤0.5mm.

9. The tab assembly according to claim 8, characterized in that: 0<W1≤0.3mm.

10. The tab assembly according to claim 9, characterized in that: 0.1mm≤W1≤0.3mm.

11. The tab assembly according to claim 3, characterized in that: Along the extending direction of the switching tab, the depth of the third groove is W2, 0<W2≤1mm.

12. The tab assembly according to claim 11, characterized in that: 0.1mm≤W2≤0.8mm.

13. The tab assembly according to claim 12, characterized in that: 0.3mm≤W2≤0.5mm.

14. A secondary battery, characterized in that: It comprises a battery cell, a packaging bag and a pole ear assembly according to any one of claims 1 to 13, wherein the battery cell is accommodated in the packaging bag, the battery cell is provided with an inner pole ear, the internal connecting section is connected to the inner pole ear, the packaging bag is provided with a packaging portion, the transfer pole ear is passed through the packaging portion, and at least part of the transfer pole ear protrudes out of the packaging bag.

15. The secondary battery according to claim 14, characterized in that: Along the width direction of the transfer tab, the bonding member includes a protruding portion and a bonding portion connected in sequence, the bonding portion is a portion overlapping the transfer tab, and the protruding portion is a portion located outside the transfer tab; along the extension direction of the transfer tab, the protruding portion has a first edge and a second edge arranged opposite to each other, and the bonding portion has a third edge and a fourth edge arranged opposite to each other, the third edge is closer to the first edge than the fourth edge, and the third edge is closer to the internal connecting section than the fourth edge; a first tangent is defined, the first tangent extends along the width direction of the transfer tab, and the first tangent is tangent to the position of the third edge farthest from the first edge; Along the extension direction of the switching tab, the distance between the first edge and the second edge is W3, the distance between the first tangent line and the second edge is W4, and -0.2mm≤W3-W4≤0.5mm.

16. The secondary battery according to claim 15, characterized in that: -0.1mm≤W3-W4≤0.3mm.

17. The secondary battery according to claim 16, characterized in that: 0≤W3-W4≤0.3mm.

18. The secondary battery according to any one of claims 15 to 17, characterized in that: An average thickness of the bonding portion within 0.1 mm of the third edge is smaller than an average thickness of the protruding portion.

19. The secondary battery according to claim 15, characterized in that: The internal connecting section is provided with a first welding area, the inner pole ear and the internal connecting section are welded and fixed in the first welding area, and along the extension direction of the transfer pole ear, the minimum distance from an edge of the first welding area to the first tangent line is W5, 0.2mm≤W5≤1mm.

20. The secondary battery according to claim 15, characterized in that The transfer tab further includes an external connection section, and along the extension direction of the transfer tab, the external connection section is connected to an end of the adhesive section away from the internal connection section; The secondary battery further includes a circuit board connected to the external connection section; defining a second tangent line, wherein the second tangent line extends along the width direction of the transfer tab, and the second tangent line is tangent to a position of the fourth edge that is farthest from the second edge; Along the extension direction of the switching tab, the distance between the second tangent line and the first edge is W6, -0.8mm≤W3-W6≤0.8mm.

21. The secondary battery according to claim 20, characterized in that: -0.5mm≤W3-W6≤0.5mm.

22. The secondary battery according to claim 21, characterized in that: -0.3mm≤W3-W6≤0.3mm.

23. The secondary battery according to claim 22, characterized in that: 0≤W3-W6≤0.3mm.

24. The secondary battery according to any one of claims 20 to 23, characterized in that: An average thickness of the bonding portion within 0.1 mm of the fourth edge is smaller than an average thickness of the protruding portion.

25. An electronic device, characterized in that: A secondary battery comprising the secondary battery according to any one of claims 14 to 24.

26. A method for preparing a secondary battery, characterized in that: include, Provide a battery cell, a packaging film, and a tab assembly as described in any one of claims 1 to 13, wherein the battery cell is provided with an inner tab, the packaging film is provided with a pit for accommodating the battery cell, and the edge of the packaging film is provided with a first sealant and a second sealant; Welding and fixing the internal connection section to the inner pole ear; The battery cell is placed in the pit, wherein, when viewed along the thickness direction of the adhesive, the orthographic projection of the adhesive bonded to the adhesive section at least partially overlaps with the orthographic projection of the first sealant or the second sealant, and the transfer tab at least partially protrudes from the edge of the packaging film; Folding the packaging film so that the first sealant and the second sealant overlap each other, wherein the switching tab extends from between the first sealant and the second sealant, and the bonding member is located between the first sealant and the second sealant; The first sealant, the second sealant and the adhesive are hot-melted to form the secondary battery.

Images