Single battery and battery pack

Abstract

The utility model provides a single battery and a battery pack, and relates to the technical field of secondary batteries. Each single battery comprises a top cover and a sealing nail; penetrating liquid injection holes are formed in the top surface and the bottom surface, and a first groove body and a second groove body are sequentially formed in the top surface in the first direction from the top surface to the bottom surface; the diameters of the first groove body, the second groove body and the liquid injection hole are sequentially reduced in the first direction; the sealing nail comprises a welding part and a main body part which are connected with each other, the welding part surrounds the main body part, the welding part is located in the first groove body and fixedly connected with the hole wall of the first groove body, the main body part covers the liquid injection hole, and part of the main body part is located in the second groove body. When the pre-welding nail pressing operation is carried out, even if the pressing contact point of the pre-welding nail pressing rod is not located at the center position of the sealing nail, the situation that the sealing nail is warped is not prone to happening, and therefore the failure rate of equipment is reduced, and the comprehensive efficiency of the equipment is improved.

Description

Technical Field

[0001] This utility model relates to the field of secondary battery technology, and in particular to a single cell battery and a battery pack. Background Technology

[0002] Individual batteries provide power to electrical devices, and with the development and application of battery technology, the requirements for individual batteries are becoming increasingly stringent.

[0003] In existing single-cell battery manufacturing processes, a pre-welding and pressing operation is required after the sealing nail is attached to the electrolyte filling port. This step often results in the sealing nail lifting problem, leading to high equipment downtime and low overall equipment efficiency. Utility Model Content

[0004] In order to solve the problems existing in the prior art, one of the objectives of this utility model is to provide a single-cell battery.

[0005] This utility model provides the following technical solution:

[0006] A single-cell battery, the single-cell battery having a first orientation, the single-cell battery comprising:

[0007] The top cover has a top surface and a bottom surface that are disposed opposite to each other in the first direction. The top surface and the bottom surface are provided with through injection holes. A first groove and a second groove are sequentially provided on the top surface along the first direction from the top surface to the bottom surface.

[0008] The first tank extends through the top surface; the first tank, the second tank, and the injection hole are sequentially connected, and their diameters decrease sequentially along the first direction; and

[0009] The sealing nail includes a welded part and a main body that are connected to each other. The welded part surrounds the main body and is located in the first tank and is fixedly connected to the hole wall of the first tank. The main body covers the injection hole and a portion of the main body is located in the second tank.

[0010] As a further optional embodiment of the single cell, the main body includes a sealing portion and a buffer portion. The sealing portion is located in the first groove, and the buffer portion is disposed between the sealing portion and the welding portion. The buffer portion is arranged around the sealing portion, and the buffer portion protrudes in the first direction toward the bottom surface, with a portion of the buffer portion located in the second groove.

[0011] As a further optional solution for the single cell, the wall of the first tank near the second tank is a first stepped surface, the wall of the second tank near the injection hole is a second stepped surface, the welding part along the first direction is attached to the first stepped surface, and the buffer part along the first direction is attached to the second stepped surface.

[0012] As a further optional feature of the single cell, the buffer portion is fitted to the inner wall of the second groove.

[0013] As a further alternative to the single cell, the sealing portion is flush with the top surface on the side opposite to the bottom surface along the first direction.

[0014] As a further optional embodiment of the single cell, the buffer portion protrudes along the first direction to form a buffer groove on the side of the buffer portion opposite to the second groove body, and the diameter of the buffer groove is smaller than the diameter of the sealing portion.

[0015] As a further optional embodiment of the single cell, the inner wall of the first tank is an inclined surface, which is inclined from the top surface to the bottom surface towards the injection hole. The welding part has an outer peripheral surface, which is in contact with the inclined surface and is fixedly connected to the inclined surface.

[0016] As a further alternative to the single cell, the side of the welded portion facing away from the bottom surface along the first direction is flush with the top surface.

[0017] Another objective of this invention is to provide a battery pack.

[0018] This utility model provides the following technical solution:

[0019] A battery pack comprising the aforementioned individual battery cells.

[0020] As a further optional feature of the battery pack, the battery pack also includes a pre-welded stud rod connected to the side of the main body facing away from the bottom surface.

[0021] The embodiments of this utility model have the following beneficial effects:

[0022] In the aforementioned single-cell battery, the top cover is provided with a first tank, a second tank, and an injection hole connected in sequence. Along a first direction, the diameters of the first tank, the second tank, and the injection hole decrease sequentially, thus achieving a double-step design. Simultaneously, the welded portion of the sealing nail is located in the first tank, while the main body portion is located in the second tank. This double-step structure effectively fixes its position. During pre-welding of the sealing nail, even if the pressing contact point of the pre-welding nail rod is not located at the center of the sealing nail, the double-step fixing method between the sealing nail and the first tank, the second tank, and the injection hole reduces the likelihood of the sealing nail lifting, thereby reducing equipment downtime and improving overall equipment efficiency.

[0023] To make the above-mentioned objectives, features and advantages of this utility model more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this utility model and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This diagram shows a partial structural schematic of a single-cell battery provided in an embodiment of the present invention;

[0026] Figure 2 An explosion diagram of a single-cell battery provided in an embodiment of the present invention is shown;

[0027] Figure 3 A schematic diagram of the pre-welded pressure studs is shown.

[0028] Explanation of key component symbols:

[0029] 10-Pre-welded stud rod;

[0030] 100-Top cover; 110-Injection hole; 120-Top surface; 130-Bottom surface; 140-First tank; 141-Inclined surface; 150-Second tank; 160-First step surface; 170-Second step surface; 200-Sealing nail; 210-Welding part; 211-Outer peripheral surface; 220-Main body; 221-Sealing part; 222-Buffer part; 222a-Buffer groove; X-First direction. Detailed Implementation

[0031] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this utility model, and should not be construed as limiting this utility model.

[0032] It should be noted that when an element is said to be "fixed to" another element, it can be directly on the other element or there may be an intervening element. When an element is said to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. Conversely, when an element is said to be "directly on" another element, there is no intervening element. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0033] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0034] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0035] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the template description is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0036] Example

[0037] Please see Figure 1 This embodiment provides a single battery cell, including but not limited to a square aluminum-cased lithium battery. The single battery cell has a first orientation X, and includes a top cover 100 and a sealing pin 200.

[0038] Please combine Figure 2 The top cover 100 has a liquid injection hole 110 extending through it along the first direction X. The top cover 100 has a top surface 120 and a bottom surface 130 disposed opposite to each other in the first direction X, and the liquid injection hole 110 extends through the top surface 120 and the bottom surface 130. A first groove 140 and a second groove 150 are sequentially provided on the top surface 120 along the first direction X from the top surface 120 to the bottom surface 130.

[0039] Understandably, the top cover 100 is sheet-like or plate-like, and the first direction X is the thickness direction of the top cover 100. The top surface 120 and the bottom surface 130 are the large surfaces of the top cover 100, that is, the surfaces where the length and width of the top cover 100 are located. The top surface 120 is part of the outer surface of the entire single cell, and the bottom surface 130 is part of the inner surface of the entire single cell.

[0040] The first tank 140 extends through the top surface 120. The first tank 140, the second tank 150, and the injection hole 110 are connected in sequence, and their diameters decrease sequentially along the first direction X.

[0041] That is to say, the diameter of the first tank 140 is larger than the diameter of the second tank 150, and the diameter of the second tank 150 is larger than the diameter of the injection hole 110. In particular, the axes of the first tank 140, the second tank 150, and the injection hole 110 coincide.

[0042] Furthermore, the sealing pin 200 includes a welded portion 210 and a main body portion 220 that are interconnected. The welded portion 210 surrounds the main body portion 220, is located within the first tank 140, and is fixedly connected to the wall of the hole in the first tank 140. The main body portion 220 covers the injection hole 110, and a portion of the main body portion 220 is located within the second tank 150.

[0043] It should be noted that during the assembly process, the welding part 210 and the hole wall of the first groove 140 are usually fixed by laser welding to achieve a sealed connection between the sealing nail 200 and the top cover 100.

[0044] In the aforementioned single-cell battery, the top cover 100 is provided with a first groove 140, a second groove 150, and a liquid injection hole 110 connected in sequence. Along the first direction X, the diameters of the first groove 140, the second groove 150, and the liquid injection hole 110 decrease sequentially, thus achieving a double-step design. Simultaneously, the welding portion 210 of the sealing nail 200 is located within the first groove 140, and a portion of the main body 220 is located within the second groove 150. These components, in conjunction with the double-step structure, effectively fix the nail's position.

[0045] When performing pre-welding and pressing operations, even if the pressing contact point of the pre-welding and pressing rod 10 is not located at the center of the sealing nail 200, the double-step fixing method between the sealing nail 200 and the first tank 140, the second tank 150 and the injection hole 110 makes it less likely for the sealing nail 200 to be dislodged, thus preventing poor nail judgment and ensuring better laser welding conditions. This reduces equipment downtime and improves overall equipment efficiency.

[0046] In addition, the double-step fixing method between the sealing nail 200 and the first tank 140, the second tank 150 and the injection hole 110 improves the sealing performance at this point, making it less likely for the electrolyte to leak.

[0047] In some embodiments, the main body 220 includes a sealing portion 221 and a buffer portion 222.

[0048] The sealing part 221 is located inside the first groove 140. The buffer part 222 is disposed between the sealing part 221 and the welding part 210, and the buffer part 222 surrounds the sealing part 221.

[0049] Understandably, the sealing part 221 is circular, and the buffer part 222 and the welding part 210 are respectively annular. The sealing part 221, the buffer part 222 and the welding part 210 are arranged sequentially from the inside to the outside, the outer edge of the sealing part 221 is connected to the inner edge of the buffer part 222, and the outer edge of the buffer part 222 is connected to the inner edge of the welding part 210.

[0050] Optionally, when processing the sealing nail 200, the sealing part 221, the buffer part 222 and the welding part 210 are integrally formed, such as by stamping or casting.

[0051] Furthermore, the buffer portion 222 protrudes along the first direction X towards the bottom surface 130, and a portion of the buffer portion 222 is located within the second groove 150.

[0052] On the one hand, the welding part 210 is located in the first tank 140, and part of the buffer part 222 is located in the second tank 150. It cooperates with the double-step structure formed by the first tank 140, the second tank 150 and the injection hole 110 to effectively fix the position of the sealing nail 200, making it less likely for the sealing nail 200 to be dislodged. At the same time, it improves the sealing performance between the sealing nail 200 and the top cover 100, making it less likely for the electrolyte to leak.

[0053] On the other hand, since the buffer portion 222 protrudes along the first direction X towards the bottom surface 130, it has multiple bending areas and is easily further bent and deformed. Therefore, the thermal stress generated during laser welding can be effectively released at the buffer portion 222. In other words, during laser welding, the hole walls of the welding portion 210 and the first groove 140 expand due to heat, causing stress to be generated inside the sealing nail 200. The buffer portion 222 can release this stress through its own deformation, thus playing a buffering role and preventing uncontrollable deformation of the sealing portion 221 and the welding portion 210. After welding, as the hole walls of the welding portion 210 and the first groove 140 gradually cool down, the stress inside the sealing nail 200 disappears, and the buffer portion 222 can smoothly recover its deformation.

[0054] Furthermore, the sealing part 221 is flush with the top surface 120 on the side opposite to the bottom surface 130 along the first direction X.

[0055] Similar to the top surface 120, the side surface of the sealing part 221 facing away from the bottom surface 130 along the first direction X is also part of the outer surface of the entire single cell, and the side surface of the sealing part 221 facing away from the bottom surface 130 along the first direction X is located on the same side of the single cell as the top surface 120.

[0056] The sealing part 221 is flush with the top surface 120 on the side opposite to the bottom surface 130 along the first direction X. After the sealing nail 200 and the top cover 100 are assembled, the flatness of the outer surface of the single battery can be guaranteed, and foreign matter residue and external force collision caused by gaps can be avoided. At the same time, good welding appearance and quality are guaranteed, which is conducive to the application of the insulating sheet of the top cover 100 in the subsequent coating process.

[0057] Specifically, the buffer portion 222 protrudes along the first direction X, so that a buffer groove 222a is formed on the side of the buffer portion 222 away from the second groove 150. The diameter of the buffer groove 222a is smaller than the diameter of the sealing portion 221.

[0058] Optionally, the cross-section of the buffer groove 222a is square. In this case, two bending areas are formed on both sides of the opening of the buffer groove 222a, and two bending areas are formed on both sides of the bottom of the buffer groove 222a, both of which are easy to bend and deform.

[0059] Furthermore, the two sides of the opening of the buffer groove 222a are rounded to further disperse stress during bending and deformation, thus preventing cracking caused by stress concentration. Similarly, the two sides of the bottom of the buffer groove 222a are also rounded to disperse stress during bending and deformation.

[0060] Alternatively, the cross-section of the buffer groove 222a can also be trapezoidal, arc-shaped, etc., and this embodiment does not limit this. When the cross-section of the buffer groove 222a is trapezoidal, the width of the groove opening is greater than the width of the groove bottom, which makes it easier to process and shape. When the cross-section of the buffer groove 222a is arc-shaped, it is preferably semi-circular.

[0061] Furthermore, the diameter of the buffer groove 222a is smaller than the diameter of the sealing part 221. That is to say, in the main body 220, the area occupied by the sealing part 221 is larger, the area occupied by the buffer part 222 is relatively smaller, and the surface of the entire main body 220 facing away from the second groove 150 is a relatively complete plane.

[0062] In some embodiments, the wall of the first tank 140 near the second tank 150 is a first stepped surface 160, and the wall of the second tank 150 near the injection hole 110 is a second stepped surface 170.

[0063] Understandably, the first step surface 160 and the second step surface 170 are two step surfaces in the double-step structure formed by the first tank 140, the second tank 150, and the injection hole 110. The second step surface 170 is located inside the first step surface 160, and the second step surface 170 is lower than the first step surface 160 along the first direction X.

[0064] In addition, the welding part 210 along the first direction X is attached to the first step surface 160, and the buffer part 222 along the first direction X is attached to the second step surface 170.

[0065] In this embodiment, both the first step surface 160 and the second step surface 170 are perpendicular to the first direction X. Correspondingly, the surface of the welding part 210 facing the first step surface 160 along the first direction X is a plane and perpendicular to the first direction X; the surface of the buffer part 222 facing the second step surface 170 along the first direction X is a plane and perpendicular to the first direction X.

[0066] Since the welding part 210 and the first step surface 160 are in surface contact, and the buffer part 222 and the second step surface 170 are in surface contact, the fit between the sealing nail 200 and the top cover 100 is tighter, and the sealing nail 200 can better fix its position, making it less likely to pry off during the pre-welding and pressing operation.

[0067] Furthermore, the buffer section 222 is fitted to the inner wall of the second groove 150.

[0068] As previously described, the buffer portion 222 protrudes along the first direction X towards the bottom surface 130, and a portion of the buffer portion 222 is located within the second groove 150. The buffer portion 222 is in contact with the inner wall of the second groove 150, specifically meaning that the protruding portion of the buffer portion 222 is in contact with the inner wall of the second groove 150.

[0069] Based on this, the outer edge of the welding part 210 is fixedly connected to the hole wall of the first groove 140, the side of the welding part 210 facing the first step surface 160 along the first direction X is in contact with the first step surface 160, the protruding part of the buffer part 222 is in contact with the inner hole wall of the second groove 150, and the side of the buffer part 222 facing the second step surface 170 along the first direction X is in contact with the second step surface 170, so that the entire sealing nail 200 is fully in contact with the double step structure formed by the first groove 140, the second groove 150 and the injection hole 110, the sealing nail 200 and the top cover 100 have the tightest fit, and the fixing effect of the sealing nail 200 is the best.

[0070] In some embodiments, the inner wall of the first tank 140 is an inclined surface 141, which is inclined from the top surface 120 to the bottom surface 130 toward the injection hole 110.

[0071] As mentioned earlier, the welding part 210 is arranged in a ring shape, and the first groove 140 is a ring-shaped groove adapted to the welding part 210. The inner wall of the first groove 140 is an inclined surface 141, specifically meaning that the cross-section of the inner wall of the first groove 140 at any position in the circumferential direction is inclined relative to the vertical direction, and the inclined surface 141 is arranged in a frustum shape. Based on this, the inclined surface 141 is inclined from the top surface 120 to the ground towards the direction close to the injection hole 110, that is, the end of the inclined surface 141 away from the second groove 150 along the first direction X has a larger opening, and the end of the inclined surface 141 closer to the second groove 150 along the first direction X has a smaller opening.

[0072] Meanwhile, the welding part 210 has an outer peripheral surface 211. The outer peripheral surface 211 fits against the inclined surface 141, and the outer peripheral surface 211 is fixedly connected to the inclined surface 141.

[0073] As mentioned above, the welding part 210 and the hole wall of the first groove 140 are usually fixed by laser welding, that is, the outer peripheral surface 211 and the inclined surface 141 are fixed by laser welding, and the connection between the outer peripheral surface 211 and the inclined surface 141 is the laser welding melting area.

[0074] On the one hand, the outer peripheral surface 211 of the welding part 210 and the inclined surface 141 of the first groove 140 are designed to be matching cones, which can better enable the welding part 210 to be embedded in the first groove.

[0075] On the other hand, during laser welding, the laser beam welds the outer peripheral surface 211 and the inclined surface 141 along the first direction X. Since the outer peripheral surface 211 and the inclined surface 141 can effectively form a fit, welding defects caused by the gap between the two can be avoided.

[0076] Furthermore, the side of the welded part 210 facing away from the bottom surface 130 along the first direction X is flush with the top surface 120.

[0077] Understandably, the side surface of the welding part 210 facing away from the bottom surface 130 along the first direction X is also part of the outer surface of the entire single cell, and the side surface of the welding part 210 facing away from the bottom surface 130 along the first direction X, the side surface of the sealing part 221 facing away from the bottom surface 130 along the first direction X, and the top surface 120 are all located on the same side of the single cell.

[0078] Based on this, the side of the welding part 210 opposite to the bottom surface 130 along the first direction X is flush with the top surface 120, which can better ensure the flatness of the outer surface of the single cell, avoid foreign object residue and external force collision caused by gaps, and at the same time ensure good welding appearance and quality, which is conducive to the application of the insulating sheet of the top cover 100 in the subsequent coating process.

[0079] In summary, in the aforementioned single-cell battery, the top cover 100 is provided with a first groove 140, a second groove 150, and an injection hole 110 connected in sequence. Along the first direction X, the diameters of the first groove 140, the second groove 150, and the injection hole 110 decrease sequentially, thus achieving a double-step design. Simultaneously, the welding portion 210 of the sealing pin 200 is located within the first groove 140, and the outer edge of the welding portion 210 is fixedly connected to the hole wall of the first groove 140. The side of the welding portion 210 facing the first step surface 160 along the first direction X is in contact with the first step surface 160. The protruding portion of the buffer portion 222 is located within the second groove 150, and the protruding portion of the buffer portion 222 is in contact with the inner hole wall of the second groove 150. The side of the buffer portion 222 facing the second step surface 170 along the first direction X is in contact with the second step surface 170. Therefore, the sealing pin 200, in conjunction with this double-step structure, can effectively fix its position. When performing the pre-welding and pressing operation, even if the pressing contact point of the pre-welding and pressing rod 10 is not located at the center of the sealing nail 200, the sealing nail 200 is not prone to lifting due to the double-step fixing method between the sealing nail 200 and the first tank 140, the second tank 150 and the injection hole 110, thereby reducing the equipment failure downtime rate and improving the overall efficiency of the equipment.

[0080] This embodiment also provides a battery pack, including the above-mentioned single battery cell.

[0081] Please see Figure 3 In some embodiments, the battery pack further includes a pre-welded stud rod 10, which is connected to the side of the main body 220 opposite to the bottom surface 130.

[0082] In use, the pre-welded pressure nail rod 10 presses the main body 220 with one end near the main body 220 along the first direction X, thereby ensuring that the sealing nail 200 and the top cover 100 always maintain a tight fit during the laser welding process, ensuring the smooth progress of the laser welding process.

[0083] In all examples shown and described herein, any specific values ​​should be interpreted as merely exemplary and not as limitations; therefore, other examples of exemplary embodiments may have different values.

[0084] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0085] The embodiments described above are merely examples of several implementations of this utility model, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of this utility model. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this utility model, and these modifications and improvements all fall within the protection scope of this utility model.

Claims

1. A single cell, characterized by, The monomer battery has a first direction (X), and comprises: a top cover (100) having oppositely arranged top and bottom surfaces (120, 130) in the first direction (X), the top and bottom surfaces (120, 130) being provided with a liquid injection hole (110) therethrough, the top surface (120) being provided with a first groove body (140) and a second groove body (150) in sequence in the first direction (X) from the top surface (120) to the bottom surface (130); the first groove body (140) penetrates the top surface (120), the first groove body (140), the second groove body (150) and the liquid injection hole (110) are in sequence communication, and the diameters of the three in the first direction (X) are in sequence decreasing; and a sealing pin (200) comprising a welding portion (210) and a main body portion (220) connected to each other, the welding portion (210) surrounding the main body portion (220), the welding portion (210) being located in the first groove body (140) and fixedly connected with the hole wall of the first groove body (140), and the main body portion (220) covering the liquid injection hole (110) and part of the main body portion (220) being located in the second groove body (150).

2. The cell according to claim 1, wherein The main body portion (220) comprises a sealing portion (221) and a buffer portion (222), the sealing portion (221) being located in the first groove body (140), the buffer portion (222) being arranged between the sealing portion (221) and the welding portion (210), the buffer portion (222) surrounding the sealing portion (221), the buffer portion (222) being protruded in the direction close to the bottom surface (130) in the first direction (X), and part of the buffer portion (222) being located in the second groove body (150).

3. The cell according to claim 2, wherein The groove wall of the first groove body (140) close to the second groove body (150) is a first step surface (160), the groove wall of the second groove body (150) close to the liquid injection hole (110) is a second step surface (170), the welding portion (210) abuts against the first step surface (160) in the first direction (X), and the buffer portion (222) abuts against the second step surface (170) in the first direction (X).

4. The cell according to claim 2, wherein The buffer portion (222) abuts against the inner hole wall of the second groove body (150).

5. The cell according to claim 2, wherein The side of the sealing portion (221) away from the bottom surface (130) in the first direction (X) is flush with the top surface (120).

6. The cell according to claim 2, wherein The buffer portion (222) is protruded in the first direction (X) to form a buffer groove (222a) on the side of the buffer portion (222) away from the second groove body (150), and the diameter of the buffer groove (222a) is smaller than that of the sealing portion (221).

7. The cell according to claim 1, wherein The inner hole wall of the first groove body (140) is an inclined surface (141) which is inclined from the top surface (120) to the bottom surface (130) towards the direction close to the liquid injection hole (110), the welding part (210) has an outer peripheral surface (211) which is in contact with the inclined surface (141) and is fixedly connected with the inclined surface (141).

8. The cell according to claim 7, wherein The side of the welding part (210) away from the bottom surface (130) along the first direction (X) is flush with the top surface (120).

9. A battery pack, characterized by, The battery pack further comprises a pre-welding dowel rod (10) connected with the main body (220) on the side away from the bottom surface (130).

10. The battery pack of claim 9, wherein, The battery pack further comprises a pre-welding dowel rod (10) connected with the main body (220) on the side away from the bottom surface (130).

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