Adapter, end cover assembly and battery

Abstract

The utility model relates to an adapter, an end cover assembly and a battery. The adapter is used for connecting the tab and the electrode terminal and comprises a first surface and a second surface which are oppositely arranged in the thickness direction, the first surface is configured to be welded to the electrode terminal through laser, the second surface is configured to be connected to the tab, and the second surface is provided with stress-free machining nicks. The stress-free machining nick is formed in the second surface deviating from the electrode terminal, that is, pressure is not applied to the adapter piece or the adapter piece is not heated in the nick machining process, so that the adapter piece keeps the original shape in the machining process and does not deform, and particularly, the welding area of the adapter piece can keep good flatness; the stress-free machining nicks are arranged on the second surface, so that the machined adapter can be tightly attached to the electrode terminal, the roughness of the second surface is improved through the stress-free machining nicks, the laser absorption rate of the adapter is increased, and the laser welding efficiency and strength between the adapter and the electrode terminal can be improved.

Description

Technical Field

[0001] The present application relates to the technical field of batteries, and particularly to an adapter, an end cover assembly, and a battery. Background Art

[0002] Laser welding has the characteristics of high efficiency and low cost, and is commonly used in the metal connection process of power batteries. For example, reliable connection can be achieved by laser penetration welding between the pole column of a power battery and an adapter. However, the metals used for the adapter (such as aluminum alloy, red copper, etc.) have relatively low laser absorption rates, which is not conducive to the direct welding between the pole column and the adapter.

[0003] In related technologies, it is usually adopted to stamp dense dimples on the surface of the adapter by using a mold to improve the laser welding effect. However, affected by the mold and stamping process, it is very difficult to control the consistency of the depth and density of the embossing, and mold stamping is likely to cause problems such as cracks, thinning of the adapter, and large mechanical stress and work hardening in the stamping part, affecting the subsequent welding process. Further, the adapter made of metals such as aluminum alloy or red copper has good plastic deformation ability, and stamping is likely to cause bending, flanging, springback, etc. of the adapter, affecting the flatness of the adapter. Summary of the Utility Model

[0004] Based on this, it is necessary to provide an adapter, an end cover assembly, and a battery for the above technical problems.

[0005] In the first aspect of the present application, an adapter is provided. The adapter is used to connect a tab and an electrode terminal. The adapter includes a first surface and a second surface that are oppositely arranged in the thickness direction. The first surface is configured to be laser welded to the electrode terminal, and the second surface is configured to be connected to the tab. The second surface has stress-free processing marks.

[0006] By providing stress-free processing marks on the second surface facing away from the electrode terminal, that is, no pressure is applied to the adapter or the adapter is not heated during the process of processing the marks, the adapter can maintain its original shape during the processing and will not be deformed. In particular, the welding area of the adapter can maintain good flatness, so that the processed adapter can be closely attached to the electrode terminal, and the stress-free processing marks increase the roughness of the second surface to increase the laser absorption rate of the adapter, thereby helping to improve the efficiency and strength of the laser welding between the adapter and the electrode terminal.

[0007] In one embodiment, the stress-free processing marks are chemical etching marks.

[0008] In one embodiment, the first surface is a flat surface.

[0009] In one embodiment, the depth of the stress-free machining notch is less than or equal to 1 / 10 of the thickness of the adapter.

[0010] In one embodiment, the cross-section of the stress-free machining notch in the thickness direction includes a first end and a second end arranged oppositely, the first end is farther from the first surface than the second end, and the size of the first end is larger than that of the second end.

[0011] In one embodiment, the width of the second end is 0.01 mm - 0.4 mm, and the interval between the first ends of adjacent stress-free machining notches is 0.01 mm - 0.4 mm.

[0012] In one embodiment, the cross-section of the stress-free machining notch in the thickness direction further includes a first side, the first side is disposed between the first end and the second end, and the included angle between the first side and the thickness direction is 1° - 60°.

[0013] In one embodiment, the stress-free machining notch includes a first notch and a second notch, the first notch and the second notch intersect with each other, and the included angle between the first notch and the second notch is 45° - 90°.

[0014] In a second aspect of the present application, a end cap assembly is provided. The end cap assembly includes: an end cap plate; an electrode terminal, the electrode terminal is connected to the end cap plate; and the adapter as described above, the first surface of the adapter is laser welded to the electrode terminal.

[0015] In a third aspect of the present application, a battery is provided. The battery includes: an electrode assembly, the electrode assembly includes a tab; a housing, the housing is used to accommodate the electrode assembly; and the end cap assembly as described above, the end cap assembly is connected to the housing so that the electrode assembly is enclosed in the housing, and the second surface of the adapter is connected to the tab. Description of the Drawings

[0016] Figure 1 It is a schematic diagram of a battery in an embodiment of the present application.

[0017] Figure 2 It is an exploded view of the battery in an embodiment of the present application from a first perspective.

[0018] Figure 3 It is an exploded view of the battery in an embodiment of the present application from a second perspective.

[0019] Figure 4 It is a schematic diagram of the adapter in an embodiment of the present application.

[0020] Figure 5 It is a schematic diagram of the cross-section of the stress-free machining notch in an embodiment of the present application.

[0021] Figure 6Schematic diagram of an adapter in an embodiment of the present application, where the stress-free processing notch includes a first notch and a second notch.

[0022] Figure 7 It is Figure 6 A partial enlarged view of area A in

[0023] Explanation of reference numerals:

[0024] 100. Battery; 10. Electrode assembly; 11. Tab; 111. First tab; 112. Second tab; 20. Housing; 30. End cover assembly; 31. End cover plate; 311. Positioning protrusion; 32. Electrode terminal; 33. Adapter; 331. First surface; 332. Second surface; 3321. Stress-free processing notch; 3321a. First end; 3321b. Second end; 3321c. First side; 3321d. First notch; 3321e. Second notch; 333. Welding part; 334. Limiting part. Detailed implementation manners

[0025] To make the above objects, features, and advantages of the present application more obvious and understandable, the following will describe the detailed implementation manners of the present application with reference to the accompanying drawings. Many specific details are set forth in the following description to fully understand the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the connotation of the present application. Therefore, the present application is not limited by the specific embodiments disclosed below.

[0026] In the description of the present application, it should be understood that if these terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. appear, the orientation or positional relationship indicated by these terms is based on the orientation or positional relationship shown in the accompanying drawings, and is 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 should not be construed as a limitation of the present application.

[0027] In addition, if these terms "first" and "second" appear, these terms are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In the description of the present application, if the term "plurality" appears, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise specifically defined.

[0028] In this application, unless otherwise clearly defined and limited, if terms such as "installed", "connected", "joined", "fixed", etc. appear, these terms should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components or the interaction relationship between two components, unless otherwise clearly defined. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0029] In this application, unless otherwise clearly defined and limited, if there is a description such as a first feature being "on" or "under" a second feature, its meaning can be that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. Moreover, the first feature being "above", "over" and "on top of" the second feature can mean that the first feature is directly above or obliquely above the second feature, or merely indicates that the first feature has a higher horizontal height than the second feature. The first feature being "under", "beneath" and "underneath" the second feature can be that the first feature is directly below or obliquely below the second feature, or merely indicates that the first feature has a lower horizontal height than the second feature.

[0030] It should be noted that if an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or there can also be an intermediate element. If an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be an intermediate element at the same time. If so, the terms "vertical", "horizontal", "up", "down", "left", "right" and similar expressions used in this application are only for the purpose of illustration and do not represent the only implementation.

[0031] Refer to Figures 1 to 3 , Figures 1 to 3 , which shows a schematic diagram of a battery 100 in an embodiment of this application. In some embodiments, the battery 100 includes an electrode assembly 10, a housing 20, and an end cap assembly 30.

[0032] The electrode assembly 10 is an important part of the battery 100 and is the component where the electrochemical reaction of the battery 100 occurs. The electrode assembly 10 can be one or more. The electrode assembly 10 is mainly formed by winding or stacking a positive electrode plate and a negative electrode plate (not shown), and usually a separator is provided between the positive electrode plate and the negative electrode plate.

[0033] Both the positive electrode plate and the negative electrode plate have a substrate and a tab 11. An active material layer is coated on the substrate, and the tab 11 is connected to the substrate. Generally, the tab 11 is made of a conductive metal material, and the tab 11 undertakes the function of transmitting current, transferring the electrical energy inside the battery 100 to an external load or transferring the electrical energy of the external load to the battery 100. The tab 11 includes a first tab 111 connected to the positive electrode substrate and a second tab 112 connected to the negative electrode substrate. The first tab 111 and the second tab 112 can be located at one end of the electrode assembly 10 together or at both ends of the electrode assembly 10 respectively. During the charging and discharging process of the battery 100, the positive electrode active material and the negative electrode active material react with the electrolyte, and the tab 11 is connected to the end cap assembly 30 to form an electric current loop.

[0034] The housing 20 is used to form the internal environment of the battery 100. The formed internal environment can be used to accommodate the electrode assembly 10, the electrolyte, and other components, and provide support and protection for the electrode assembly 10, the electrolyte, and other components. Generally, the housing 20 is provided with an open end to facilitate putting the electrode assembly 10, the electrolyte, and other components into the housing 20. The housing 20 can be of various shapes and sizes, such as cuboid, cylindrical, hexagonal prism, etc. Specifically, the shape of the housing 20 can be determined according to the specific shape and size of the electrode assembly 10. The material of the housing 20 can be various, for example, copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and the embodiments of the present application do not make special restrictions on this.

[0035] The end cap assembly 30 is connected to the housing 20 to close the open end of the housing 20, forming a closed internal environment, thereby sealing and fixing the electrode assembly 10 inside the housing 20, isolating the internal environment of the battery 100 from the external environment, which helps the battery 100 to be used normally for a long time.

[0036] In some embodiments, referring to Figure 2 and Figure 3 , the end cap assembly 30 includes an end cap plate 31, an electrode terminal 32, and an adapter 33. The end cap plate 31 is connected to the open end of the housing 20, thereby closing the housing 20 and enabling the electrode assembly 10 to be stably accommodated inside the housing 20. Without limitation, the shape of the end cap plate 31 can be adapted to the shape of the housing 20 to cooperate with the housing 20. Optionally, the end cap plate 31 can be made of a material with a certain hardness and strength (such as aluminum alloy). In this way, the end cap plate 31 is not easily deformed when being squeezed or collided, enabling the battery 100 to have higher structural strength and improved safety performance.

[0037] The electrode terminal 32 is used for electrically connecting with the electrode assembly 10 to input or output the electric energy of the battery 100. The electrode terminal 32 is fixed on the end cover plate 31. Feasibly, the electrode terminal 32 and the end cover plate 31 are integrally formed. The tab 11 includes a first tab 111 and a second tab 112. Correspondingly, the electrode terminal 32 includes a first electrode terminal 321 and a second electrode terminal 322. The first electrode terminal 321 is connected to the first tab 111, and the second electrode terminal 322 is connected to the second tab 112. Thus, the first tab 111 is electrically connected to the first electrode terminal 321, and the second tab 112 is electrically connected to the second electrode terminal 322 to form a current loop.

[0038] The adapter 33 is used to realize the electrical connection between the electrode terminal 32 and the tab 11, avoid damage to the tab 11 and the electrode terminal 32 when the tab 11 and the electrode terminal 32 are directly connected, ensure the stability of the connection between the electrode terminal 32 and the tab 11, and the adapter 33 can electrically connect the tab 11 and the electrode terminal 32. Thus, the current is transmitted from the electrode to the tab 11, from the tab 11 to the adapter 33, from the adapter 33 to the electrode terminal 32, and from the electrode terminal 32 to the external load, ensuring the normal operation of the battery 100 and current transmission. Generally, the adapter 33 is prepared from a metal material with good electrical and thermal conductivity (such as aluminum alloy, copper alloy, etc.), and the adapter 33 and the electrode terminal 32 are connected by laser penetration welding.

[0039] The adapter 33 in the present application will be introduced in detail below.

[0040] In some embodiments, referring to Figures 2 to 5 , the adapter 33 includes a first surface 331 and a second surface 332 that are oppositely arranged in the thickness direction. The first surface 331 faces the electrode terminal 32, and the first surface 331 is laser welded to the electrode terminal 32. The second surface 332 faces away from the electrode terminal 32, and the second surface 332 is connected to the tab 11. The second surface 332 has a stress-free machining mark 3321, and the stress-free machining mark 3321 is used to increase the laser absorption rate of the adapter 33. It should be noted that the stress-free machining mark 3321 refers to a mark obtained by machining the adapter 33 without applying pressure or heating the adapter 33.

[0041] By providing a stress-free machining notch 3321 on the second surface 332 facing away from the electrode terminal 32, that is, not applying pressure or heating the adapter 33 during the machining of the notch, the adapter 33 can maintain its original shape during the machining process without deformation. In particular, the welding area of the adapter 33 can maintain good flatness, enabling the machined adapter 33 to fit tightly with the electrode terminal 32. Moreover, the stress-free machining notch 3321 increases the roughness of the second surface 332 to enhance the laser absorption rate of the adapter 33, thereby contributing to improving the efficiency and strength of the laser welding between the adapter 33 and the electrode terminal 32.

[0042] Furthermore, the stress-free machining notch 3321 is a chemical etching notch. By immersing the second surface 332 of the adapter 33 in a specific chemical solution, the surface morphology of the second surface 332 is changed through a chemical reaction, thereby machining multiple notches on the second surface 332 to increase the roughness of the second surface 332. When the second surface 332 is irradiated with laser for welding, the second surface 332 can increase the absorption of laser energy, thus improving the effect of laser welding.

[0043] During the chemical etching process, no additional pressure or heat is applied, avoiding the influence of mechanical stress or thermal stress on the adapter 33 after machining, which may cause deformation of the adapter 33. Thus, the flatness of the adapter 33 is improved, enabling the adapter 33 to fit tightly with the first electrode terminal 321, avoiding poor welding between the adapter 33 and the electrode terminal 32 during laser welding, and improving the welding strength. In other embodiments, stress-free machining of the second surface 332 can also be achieved through ion implantation, electrochemical machining, etc., and stress-free machining notches 3321 are formed on the second surface 332.

[0044] Specifically in this embodiment, the first surface 331 is a plane. The first surface 331 is the surface that fits against the electrode terminal 32. By not machining the first surface 331, the adapter 33 can maintain a certain thickness and strength, avoiding a reduction in the strength of the adapter 33 due to stress-free machining notches 3321 on both surfaces of the adapter 33, and helping to prevent the thickness of the adapter 33 from being reduced too much, which may cause the laser to penetrate the adapter 33 or even the electrode terminal 32 during laser welding.

[0045] Preferably, the depth H1 of the stress-free machining notch 3321 is less than or equal to 1 / 10 of the thickness H2 of the adapter 33. Thus, the absorption rate of laser is increased through the stress-free machining notch 3321, improving the efficiency and strength of laser welding, and enabling the adapter 33 to still have relatively high strength, avoiding the laser from directly acting on the electrode terminal 32 by penetrating the adapter 33. Optionally, the thickness H2 of the adapter 33 is 0.2 mm - 4 mm.

[0046] In some embodiments, referring to Figure 4 and Figure 5 , the cross-section of the stress-free machining notch 3321 along the thickness direction includes a relatively arranged first end 3321a and a second end 3321b. The first end 3321a is farther from the first surface 331 than the second end 3321b, and the size of the first end 3321a is larger than that of the second end 3321b, that is, the stress-free machining notch 3321 with an upper-wide and lower-narrow structure is formed. The upper-wide and lower-narrow structure may include a trapezoid, a V shape, or a U shape.

[0047] By forming the stress-free machining notch 3321 with an upper-wide and lower-narrow structure, when the laser is vertically irradiated on the surface of the stress-free machining notch 3321, an incident angle less than 90° will be formed with the surface of the stress-free machining notch 3321. Thus, the laser will be reflected in the middle of the stress-free machining notch 3321, increasing the absorption of the laser by the second surface 332.

[0048] Preferably, the width L1 of the second end 3321b is 0.01 mm - 0.4 mm, that is, the size of the bottom of the stress-free machining notch 3321 is small, avoiding too much laser reflected through the bottom of the stress-free machining notch 3321, and thus affecting the absorption rate of the laser by the second surface 332.

[0049] Preferably, the interval L2 between the first ends 3321a of adjacent stress-free machining notches 3321 is 0.01 mm - 0.4 mm, that is, the interval L2 between adjacent stress-free machining notches 3321 is small, avoiding a large plane between the stress-free machining notches 3321 and reflecting too much laser, which affects the absorption rate of the laser by the second surface 332.

[0050] Furthermore, the cross-section of the stress-free machining notch 3321 along the thickness direction further includes a first side 3321c. The first side 3321c is arranged between the first end 3321a and the second end 3321b, and the included angle α between the first side 3321c and the thickness direction is 1° - 60°. Thus, the laser irradiated on the first side 3321c will be emitted by the first side 3321c into the interior of the stress-free machining notch 3321, and the laser will be repeatedly irradiated and reflected inside the stress-free machining notch 3321, increasing the absorption rate of the laser by the second surface 332.

[0051] In some embodiments, referring to Figure 6 and Figure 7, The stress-free machining notch 3321 includes a first notch 3321d and a second notch 3321e, and the first notch 3321d and the second notch 3321e intersect with each other. The first notch 3321d and the second notch 3321e distributed by intersection can further increase the roughness and effective surface area of the second surface 332, so that the laser can be more effectively absorbed by the adapter 33, thereby making the welding process between the adapter 33 and the electrode terminal 32 more stable and efficient. Moreover, the first notch 3321d and the second notch 3321e can increase the heat exchange surface area between the adapter 33 and the surrounding environment, thereby promoting heat conduction, reducing thermal stress and deformation, and improving the stability and controllability of welding. Optionally, the included angle between the first notch 3321d and the second notch 3321e is 45°-90°. In other embodiments, the stress-free machining notch 3321 may only include the first notch 3321d or the second notch 3321e.

[0052] Optionally, the stress-free machining notch 3321 covers the second surface 332, or the stress-free machining notch 3321 is only arranged on the second surface 332 corresponding to the welding area of the first surface 331.

[0053] In a feasible embodiment, the adapter 33 includes a welding portion 333, and the welding portion 333 is used for welding connection with the electrode terminal 32 and the tab 11. The first surface 331 of the welding portion 333 is connected to the electrode terminal 32 by laser welding, and the second surface 332 of the welding portion 333 is connected to the tab 11 by ultrasonic welding.

[0054] Furthermore, referring to Figure 2 and Figure 4 , the adapter 33 further includes a limiting portion 334. The limiting portion 334 is connected to the welding portion 333, and the limiting portion 334 is used to achieve the alignment connection between the adapter 33 and the electrode terminal 32. Specifically, a positioning protrusion 311 is provided on the surface of the end cover plate 31 facing the adapter 33, and the limiting portion 334 is configured as a positioning groove matching the positioning protrusion 311. When the positioning groove is connected to the positioning protrusion 311, the welding portion 333 can be aligned with the electrode terminal 32, which helps the welding between the adapter 33 and the electrode terminal 32. For example, a U-shaped positioning groove is provided to match the U-shaped protrusion of the adapter 33.

[0055] Furthermore, an installation groove is formed in the electrode terminal 32 in a direction away from the adapter 33. The welding portion 333 of the adapter 33 protrudes from the limiting portion 334 in a direction towards the electrode terminal 32, and the first surface 331 of the welding portion 333 protrudes from the first surface 331 of the limiting portion 334. Thus, during installation, it is possible to prevent the inversion of the first surface 331 and the second surface 332 from affecting the welding strength.

[0056] In other embodiments, the adapter 33 may be provided with a positioning groove on the first surface 331 of the limiting portion 334, and a positioning protrusion matching the positioning groove is provided on the surface of the end cover plate 31 facing the adapter 33, so as to avoid the inversion of the first surface 331 and the second surface 332 during positioning and improve the welding efficiency.

[0057] In an embodiment of the present application, the electrode terminal 32 includes a third surface 323 and a fourth surface 324 which are oppositely arranged. The third surface 323 faces away from the adapter 33 and is arranged outside the end cover plate 31, and the fourth surface 324 faces the adapter 33.

[0058] When the battery 100 is assembled and fixed, it includes the following steps: placing the electrode assembly 10 in the housing 20; assembling the end cover assembly 30. Specifically, fixing the electrode terminal 32 to the end cover plate 31, and then fixing the first surface 331 of the adapter 33 to the fourth surface 324 of the electrode terminal 32 by laser penetration welding to complete the assembly of the end cover assembly 30; connecting the end cover assembly 30 and the electrode assembly 10. Specifically, fixing and connecting the second surface 332 of the adapter 33 to the tab 11 by ultrasonic welding; connecting the housing 20 and the end cover assembly 30. Specifically, connecting the end cover plate 31 to the housing 20 to complete the assembly of the battery 100.

[0059] It should be noted that the order of the steps of assembling the end cover assembly 30, placing the electrode assembly 10 in the housing 20, and connecting the end cover assembly 30 and the electrode assembly 10 is not limited. For example, first assemble the end cover assembly 30, then connect the end cover assembly 30 and the electrode assembly 10, and finally place the electrode assembly 10 connected to the end cover assembly 30 in the housing 20; or first assemble the end cover assembly 30, then place the electrode assembly 10 in the housing 20, and finally connect the end cover assembly 30 and the electrode assembly 10; or first place the electrode assembly 10 in the housing 20, then assemble the end cover assembly 30, and finally connect the end cover assembly 30 and the electrode assembly 10.

[0060] The adapter 33 is provided with a stress-free processing scratch 3321 on the second surface 332 facing away from the electrode terminal 32, that is, no pressure is applied to the adapter 33 or the adapter 33 is heated during the process of processing the scratch, so that the adapter 33 maintains its original shape during the processing and does not deform. In particular, the welding area of the adapter 33 can maintain good flatness, so that the processed adapter 33 can be closely attached to the electrode terminal 32, and the stress-free processing scratch 3321 increases the roughness of the second surface 332 to increase the laser absorption rate of the adapter 33, thereby contributing to the laser welding between the adapter 33 and the electrode terminal 32.

[0061] Laser penetration welding is performed through the adapter 33 and the electrode terminal 32, without the need to process the adapter 33 any further. Moreover, laser welding is a non-contact welding method, featuring high welding efficiency, high machining precision, and high automation. It can ensure a reliable connection strength between the adapter 33 and the electrode terminal 32, thereby reducing the production cost of the battery 100, improving the production efficiency of the battery 100, and enhancing the production quality of the battery 100.

[0062] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0063] The above-described embodiments merely represent several implementation manners of the present application. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the appended claims.

Claims

1. A transfer piece, used to connect a tab and an electrode terminal, characterized in that: The adapter includes a first surface and a second surface that are arranged opposite to each other in a thickness direction, the first surface is configured to be laser welded to the electrode terminal, the second surface is configured to be connected to the tab, and the second surface has a stress-free processing notch.

2. The adapter according to claim 1, characterized in that: The stress-free processing marks are chemical etching marks.

3. The adapter according to claim 1, characterized in that: The first surface is a plane.

4. The adapter according to claim 1, characterized in that: The depth of the stress-free machining notch is less than or equal to 1 / 10 of the thickness of the adapter.

5. The adapter according to claim 1, characterized in that: A cross section of the stress-free machining notch along the thickness direction includes a first end and a second end that are oppositely disposed, the first end is farther away from the first surface than the second end, and a size of the first end is larger than a size of the second end.

6. The adapter according to claim 5, characterized in that: The width of the second end is 0.01 mm-0.4 mm, and the interval between the first ends of adjacent stress-free processing notches is 0.01 mm-0.4 mm.

7. The adapter according to claim 5, characterized in that: The cross section of the stress-free processing notch along the thickness direction further includes a first side edge, the first side edge is arranged between the first end and the second end, and an angle between the first side edge and the thickness direction is 1°-60°.

8. The adapter according to claim 1, characterized in that: The stress-free processing notch includes a first notch and a second notch, the first notch and the second notch intersect each other, and an angle between the first notch and the second notch is 45°-90°.

9. An end cap assembly, characterized in that: The end cap assembly comprises: End cover plate; an electrode terminal connected to the end cover plate; and The adapter as described in any one of claims 1 to 8, wherein the first surface of the adapter is laser welded to the electrode terminal.

10. A battery, characterized in that: The battery comprises: An electrode assembly, the electrode assembly comprising a tab; a housing for accommodating the electrode assembly; and The end cap assembly as described in claim 9, wherein the end cap assembly is connected to the shell so that the electrode assembly is enclosed in the shell, and the second surface of the adapter is connected to the electrode ear.

Images