Battery

Abstract

Disclosed in the present application is a battery. The battery comprises: a case and a battery cell. An accommodating cavity is provided in the case, and the case has a first side wall. The battery cell is arranged in the accommodating cavity, and the battery cell comprises a tab assembly. The tab assembly is welded to the first side wall by means of at least two linear weld seams. The at least two linear weld seams are sequentially arranged in a first direction, the ends of the linear weld seams that are close to the first side wall run into the first side wall, and in the wall thickness direction of the first side wall, the ends of adjacent linear weld seams running into the first side wall are staggered. The battery of the present application solves the problems in the prior art of welding between a tab and a case in a battery not being firm enough, and the internal resistance at a connecting position being large.

Description

Battery

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on December 18, 2023, with application number 202323465027.1 and application name “Battery”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the technical field of lithium battery production, and in particular to a battery. Background Art

[0003] Lithium battery technology is increasingly used in energy fields such as 3C consumer electronics, power batteries, and energy storage. It can be divided into three categories based on the packaging shell: stainless steel cylindrical batteries, aluminum or stainless steel shell square batteries, and soft-pack batteries. Among them, stainless steel cylindrical batteries and aluminum or stainless steel shell square batteries are all made of metal.

[0004] In steel-cased lithium-ion batteries, the tabs are typically connected to the steel casing using laser welding. However, existing welds between the tabs and the steel casing often form multiple circular or spiral patterns, making it difficult to detect edge contours during visual inspection. Furthermore, the welds between the tabs and the steel casing are not strong enough, resulting in high internal resistance at the joint, which can compromise battery safety.

[0005] Application Contents

[0006] The main purpose of the present application is to provide a battery to at least solve the problem in the prior art that the welding between the tab and the shell is not firm enough and the internal resistance at the connection is large.

[0007] According to one aspect of the present application, there is provided a battery comprising:

[0008] A housing is provided with an accommodating cavity and has a first side wall;

[0009] The battery cell is arranged in the accommodating cavity, and the battery cell includes a tab assembly;

[0010] Among them, the tab assembly is welded to the first side wall by at least two linear welds, and the at least two linear welds are arranged in sequence along the first direction. The end of the linear weld close to the first side wall is penetrated into the first side wall, and along the wall thickness direction of the first side wall, the ends of the two adjacent linear welds penetrating into the first side wall are arranged at different heights.

[0011] Furthermore, the number of linear welds is greater than or equal to 3 and less than or equal to 5.

[0012] Furthermore, the linear weld includes a first weld, a second weld, a third weld, a fourth weld and a fifth weld arranged in sequence along the first direction, and the first weld, the second weld, the third weld, the fourth weld and the fifth weld are staggered in height along the thickness direction of the first side wall.

[0013] Furthermore, the depth of penetration of the second weld into the first side wall is greater than the depth of penetration of the first weld, the third weld, the fourth weld, and the fifth weld into the first side wall; and / or,

[0014] The depth to which the third weld penetrates the first side wall is the same as the depth to which the fifth weld penetrates the first side wall; and / or,

[0015] The first weld penetrates the first sidewall to the same depth as the fourth weld penetrates the first sidewall; and / or,

[0016] The depths at which the first weld and the fourth weld penetrate into the first side wall are greater than the depths at which the third weld and the fifth weld penetrate into the first side wall.

[0017] Furthermore, along the first direction, the sum H of the widths of the first weld, the second weld, the third weld, the fourth weld, and the fifth weld satisfies the relationship 170 μm < H < 220 μm.

[0018] Furthermore, the tab assembly includes a first surface facing away from the first sidewall, a first wave valley is defined between the first weld and the second weld, a second wave valley is defined between the second weld and the third weld, a third wave valley is defined between the third weld and the fourth weld, and a fourth wave valley is defined between the fourth weld and the fifth weld.

[0019] Wherein, along the thickness direction of the first sidewall, the vertical distance from the third wave valley to the first surface is greater than the vertical distances from the first wave valley, the second wave valley, and the fourth wave valley to the first surface; and / or,

[0020] The vertical distance from the second wave valley to the first surface is smaller than the vertical distances from the first wave valley and the fourth wave valley to the first surface; and / or,

[0021] A vertical distance from the first wave valley to the first surface is greater than a vertical distance from the fourth wave valley to the first surface.

[0022] Furthermore, along the first direction, among two adjacent troughs, the vertical distance between the third trough and the fourth trough is greater than the vertical distance between the remaining two adjacent troughs, and the vertical distance between the second trough and the third trough is less than the vertical distance between the remaining two adjacent troughs.

[0023] Further, the first weld includes a first wave peak, the second weld includes a second wave peak, the third weld includes a third wave peak, the fourth weld includes a fourth wave peak, and the fifth weld includes a fifth wave peak;

[0024] Wherein, along the first direction, of two adjacent wave crests, the vertical distance between the second wave crest and the third wave crest is greater than the vertical distance between the remaining two adjacent wave crests; and / or,

[0025] The vertical distance between the fourth wave crest and the fifth wave crest is smaller than the vertical distance between the remaining two adjacent wave crests; and / or,

[0026] A vertical distance between the first wave crest and the second wave crest is greater than a vertical distance between the third wave crest and the fourth wave crest.

[0027] Furthermore, the maximum depth Kmax of the linear weld penetrating into the first side wall and the thickness J of the first side wall satisfy the relationship of 50%≤Kmax / J≤90%.

[0028] Furthermore, the linear weld includes a raised section, the raised section protrudes from the surface of the tab assembly away from the first side wall, and a height W of the raised section satisfies the relationship 20 μm<W<30 μm.

[0029] Furthermore, the width h of the linear weld satisfies the relationship 40 μm<h<50 μm.

[0030] Furthermore, the length D of the linear weld and the width M of the tab assembly satisfy the relationship of 60%≤D / M≤70%.

[0031] Compared to the prior art, the welds in this application are linear welds. Linear welds are easily detectable as weld marks during visual inspection. Compared to concentric or spiral welds, they have regular trajectories, low internal resistance at the connection, and increased connection area between the tab assembly and the first sidewall. Furthermore, in this application, the ends of two adjacent linear welds passing through the first sidewall are arranged at different heights. This arrangement prevents the welding trajectories of the two adjacent welds from merging, and the height difference between the ends of adjacent welds passing through the first sidewall creates a pinning effect on the welds, thereby enhancing the weld strength between the tab assembly and the housing. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0033] FIG1 is a schematic diagram of a partial structure of a battery disclosed in the present application (including a battery cell, a tab assembly, and a first side wall of a housing);

[0034] FIG2 is a schematic diagram of a partial structure of a first surface of a tab assembly in a battery disclosed in the present application at a first viewing angle;

[0035] FIG3 is a schematic diagram of a portion of the first surface structure of a tab assembly in a battery disclosed in the present application at a second viewing angle;

[0036] FIG4 is a schematic diagram of a structure of welding a tab assembly to a battery shell disclosed in the present application;

[0037] FIG5 is another schematic diagram of the structure of welding the tab assembly and the battery shell disclosed in this application;

[0038] FIG6 is a schematic diagram showing another structure of welding the tab assembly to the battery shell disclosed in the present application, which is different from FIG4 and FIG5 .

[0039] The above drawings include the following reference numerals:

[0040] 10. Shell; 11. First side wall; 20. Tab assembly; 21. First surface; 31. First weld; 32. Second weld; 33. Third weld; 34. Fourth weld; 35. Fifth weld; 40. Battery cell; 301. First wave peak; 302. Second wave peak; 303. Third wave peak; 304. Fourth wave peak; 305. Fifth wave peak; 311. First wave valley; 312. Second wave valley; 313. Third wave valley; 314. Fourth wave valley; 321. Raised section. DETAILED DESCRIPTION

[0041] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0042] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0043] Unless otherwise specifically stated, the relative arrangement of the parts and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present application. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the drawings are not drawn according to actual proportional relationships. The techniques, methods and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the techniques, methods and equipment should be considered as part of the authorization specification. In all examples shown and discussed here, any specific values ​​should be interpreted as being merely exemplary, not as limitations. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that similar numbers and letters represent similar items in the following figures, and therefore, once an item is defined in one figure, it does not need to be further discussed in subsequent figures.

[0044] 1 to 6 , according to an embodiment of the present application, a battery is provided. The battery includes a housing 10 and a battery cell 40 .

[0045] The housing 10 is provided with a housing cavity, and the housing 10 has a first sidewall 11. A battery cell 40 is disposed within the housing cavity, and the battery cell 40 includes a tab assembly 20. The tab assembly 20 is welded to the first sidewall 11 via at least two linear welds, with the at least two linear welds being arranged sequentially along a first direction (e.g., the X direction in FIG. 4 ), with one end of the linear weld proximal to the first sidewall 11 penetrating the first sidewall 11. Furthermore, along the wall thickness direction of the first sidewall 11 (e.g., the Y direction in FIG. 4 ), the ends of two adjacent linear welds penetrating the first sidewall 11 are arranged at different heights.

[0046] Compared to the prior art, the weld in this embodiment is a linear weld. A linear weld is easily detectable as a weld mark during visual inspection. Compared to concentric or spiral welds, the weld has a regular trajectory, low internal resistance at the connection, and increases the connection area between the tab assembly 20 and the first side wall 11. Furthermore, in this embodiment, the ends of two adjacent linear welds passing through the first side wall 11 are arranged at different heights. This arrangement prevents the weld trajectories of the two adjacent welds from merging, and the height difference between the ends of adjacent welds passing through the first side wall 11 creates a pinning effect on the weld, thereby improving the weld strength between the tab assembly 20 and the housing 10.

[0047] Furthermore, the number of linear welds is greater than or equal to 3 and less than or equal to 5. In this embodiment, when there are fewer than three linear welds, the weld print area is small, the internal resistance at the connection between the tab assembly 20 and the housing 10 is large, and the safety performance of the battery is easily reduced. At the same time, the heat accumulation effect of the weld during welding is poor, resulting in the linear weld penetrating the first side wall 11 to a too low depth, low weld tensile strength, and easy separation of the tab assembly 20 from the housing 10. If there are more than five linear welds, on the one hand, the welding time is long and production efficiency is low; on the other hand, the multiple linear welds reduce the strength of the housing 10, resulting in a shortened battery life.

[0048] As shown in FIG4 , the linear weld includes a first weld 31, a second weld 32, a third weld 33, a fourth weld 34 and a fifth weld 35 arranged in sequence along the first direction, and the first weld 31, the second weld 32, the third weld 33, the fourth weld 34 and the fifth weld 35 are staggered in height along the thickness direction of the first side wall 11.

[0049] Specifically, the five welds are staggered in height, which means that the depth of the first weld 31 penetrating into the first side wall 11, the depth of the second weld 32 penetrating into the first side wall 11, the depth of the third weld 33 penetrating into the first side wall 11, the depth of the fourth weld 34 penetrating into the first side wall 11, and the depth of the fifth weld 35 penetrating into the first side wall 11 are staggered in height. When the five welds are staggered in height, each weld produces a pinning effect, and the heat accumulation effect of the welds during welding is good, which makes it easy to increase the depth of the welds penetrating into the first side wall 11, thereby improving the welding firmness of the tab assembly 20 and the shell 10 to a certain extent.

[0050] Furthermore, the depth to which the second weld 32 penetrates into the first sidewall 11 is greater than the depth to which the first weld 31, the third weld 33, the fourth weld 34, and the fifth weld 35 penetrate into the first sidewall 11. Optionally, the depth to which the third weld 33 penetrates into the first sidewall 11 is the same as the depth to which the fifth weld 35 penetrates into the first sidewall 11. Optionally, the depth to which the first weld 31 penetrates into the first sidewall 11 is the same as the depth to which the fourth weld 34 penetrates into the first sidewall 11. Optionally, the depth to which the first weld 31 and the fourth weld 34 penetrate into the first sidewall 11 is greater than the depth to which the third weld 33 and the fifth weld 35 penetrate into the first sidewall 11.

[0051] Preferably, as shown in FIG4 , when welding the tab assembly 20 , the welding is performed in the order of the third weld 33 , the first weld 31 , the second weld 32 , the fifth weld 35 , and the fourth weld 34 . Since the second weld 32 is welded after the third weld 33 and the first weld 31 are welded, the heat on the first weld 31 and the third weld 33 is relatively high, resulting in a good heat accumulation effect. Therefore, when welding the second weld 32 , the depth of the second weld 32 penetrating into the first side wall 11 is greater than that of the first weld 31 and the third weld 33 . Similarly, after welding the fifth weld 35 , the fourth weld 34 is welded, and the depth of the fourth weld 34 penetrating into the first side wall 11 is greater than that of the third weld 33 and the fourth weld 34 . Since the temperature of the third weld 33 decreases when the fourth weld 34 is welded, the depth of the fourth weld 34 penetrating into the first side wall 11 is lower than the depth of the second weld 32 penetrating into the first side wall 11 .

[0052] According to the welding sequence of this embodiment, the depths of the first weld 31, the second weld 32, the third weld 33, the fourth weld 34, and the fifth weld 35 penetrating into the first side wall 11 are staggered in height, so that the welds produce a pinning effect within the first side wall 11, thereby enhancing the weld strength. Of course, the welding sequence of the five welds may also be other, as long as the five welds are staggered in height along the first direction after welding.

[0053] It is worth mentioning that, in the two embodiments shown in Figures 5 and 6 , the welding effect of the five welds arranged along the thickness direction of the first side wall 11, with adjacent welds arranged at different heights, is still better than that of circular welding or spiral welding. In the embodiment shown in Figure 5 , the welding order of the five linear welds is, in order: the third weld 33, the second weld 32, the first weld 31, the fourth weld 34, and the fifth weld 35. In the embodiment shown in Figure 6 , the welding order of the five linear welds is, in order: the third weld 33, the second weld 32, the fourth weld 34, the first weld 31, and the fifth weld 35.

[0054] Furthermore, along the first direction, the sum of the widths H of the first weld 31, the second weld 32, the third weld 33, the fourth weld 34, and the fifth weld 35 satisfies the relationship 170 μm < H < 220 μm, and may be, for example, 175 μm, 180 μm, 185 μm, 190 μm, 195 μm, 200 μm, 205 μm, 210 μm, and 215 μm. When the sum of the widths H of the welds is within the above range, the welding strength between the tab assembly 20 and the housing 10 is high, and the total weld width H is moderate, which does not result in an excessively large total weld, thereby reducing the structural strength of the tab assembly 20 and the housing 10. However, when the total weld width H is less than or equal to 170 μm, the total weld width H is small, the welding strength is low, and separation of the tab assembly 20 from the housing 10 is likely to occur. When the total weld width H is greater than or equal to 220 μm, the total weld width H is too large, which increases the internal stress of the tab assembly 20 and the shell 10 and reduces the structural strength of the tab assembly 20 and the shell 10, which may easily cause damage to the tab assembly 20 and the shell 10 when subjected to external force.

[0055] In addition, the tab assembly 20 includes a first surface 21 facing away from the first sidewall 11. A first trough 311 is defined between the first weld 31 and the second weld 32, a second trough 312 is defined between the second weld 32 and the third weld 33, a third trough 313 is defined between the third weld 33 and the fourth weld 34, and a fourth trough 314 is defined between the fourth weld 34 and the fifth weld 35. The welding is performed sequentially in the order of the third weld 33, the first weld 31, the second weld 32, the fifth weld 35, and the fourth weld 34. Along the thickness direction of the first sidewall 11, the vertical distance from the third trough 313 to the first surface 21 is greater than the vertical distances from the first trough 311, the second trough 312, and the fourth trough 314 to the first surface 21. Optionally, the vertical distance from the second wave valley 312 to the first surface 21 is smaller than the vertical distances from the first wave valley 311 and the fourth wave valley 314 to the first surface 21. Optionally, the vertical distance from the first wave valley 311 to the first surface 21 is greater than the vertical distance from the fourth wave valley 314 to the first surface 21.

[0056] In this embodiment, along the first direction, the first wave valley 311, the second wave valley 312, the third wave valley 313 and the fourth wave valley 314 are arranged in a high and low staggered manner, and the welds on both sides of each wave valley have a good pinning effect. The high and low arrangement between adjacent wave valleys means that the welds between the two wave valleys are better fused with the adjacent welds.

[0057] Furthermore, along the first direction, the vertical distance between the third trough 313 and the fourth trough 314 of two adjacent troughs is greater than the vertical distance between the other two adjacent troughs, and the vertical distance between the second trough 312 and the third trough 313 is less than the vertical distance between the other two adjacent troughs.

[0058] Specifically, after welding in the order of third weld 33, first weld 31, second weld 32, fifth weld 35, and fourth weld 34, fourth weld 34 has a greater width due to the greater heat accumulation in fourth weld 34 and the better fusion of third weld 33, fourth weld 34, and fifth weld 35. Therefore, the vertical distance between third and fourth troughs 313 and 314 is greater than the vertical distance between the remaining two adjacent troughs. Conversely, third weld 33, being welded first, has poor heat accumulation. After welding second weld 32 and fourth weld 34, its width remains almost unchanged, resulting in the smallest vertical distance between second and third troughs 312 and 313. Furthermore, along the first direction, the greater the vertical distance between two adjacent troughs, the better the fusion and more stable the weld between the two troughs and the surrounding welds.

[0059] Furthermore, the first weld 31 includes a first wave peak 301, the second weld 32 includes a second wave peak 302, the third weld 33 includes a third wave peak 303, the fourth weld 34 includes a fourth wave peak 304, and the fifth weld 35 includes a fifth wave peak 305. Along the first direction, of two adjacent wave peaks, the vertical distance between the second wave peak 302 and the third wave peak 303 is greater than the vertical distances between the remaining two adjacent wave peaks. Optionally, the vertical distance between the fourth wave peak 304 and the fifth wave peak 305 is less than the vertical distances between the remaining two adjacent wave peaks. Optionally, the vertical distance between the first wave peak 301 and the second wave peak 302 is greater than the vertical distance between the third wave peak 303 and the fourth wave peak 304. In this embodiment, along the first direction, a larger vertical distance between two adjacent wave peaks indicates better weld heat accumulation between the adjacent wave peaks, higher weld strength, and better weld pinning.

[0060] Furthermore, the maximum depth Kmax of the linear weld penetrating into the first side wall 11 and the thickness J of the first side wall 11 satisfy the relationship of 50% ≤ Kmax / J ≤ 90%. For example, Kmax / J can be 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, and 90%. When Kmax / J is within the above range, the linear weld has a high tensile strength and there is no risk of melting through the first side wall 11. When Kmax / J is less than 50%, the tensile strength of the linear weld is low, which can easily cause the tab assembly 20 and the shell 10 to separate from each other when subjected to external forces. When Kmax / J is greater than 90%, the overall rigidity of the shell 10 is reduced, and when Kmax / J is greater than or equal to 100%, the linear weld melts through the shell 10, causing damage to the shell 10.

[0061] Furthermore, the linear weld includes a raised segment 321 that protrudes from the surface of the tab assembly 20 facing away from the first sidewall 11. The height W of the raised segment 321 satisfies the relationship 20 μm < W < 30 μm. For example, W can take values ​​of 21 μm, 22 μm, 23 μm, 24 μm, 25 μm, 26 μm, 27 μm, 28 μm, and 29 μm. Within this range, the height W of the raised segment 321 of the linear weld can be controlled within a relatively small range without significantly affecting the tab assembly 20. However, when W is greater than or equal to 30 μm, the raised segment 321 is too high, reducing the rigidity of the tab assembly 20. Of course, if the welding process allows, the optimal value of W satisfies the relationship 0 μm < W < 30 μm. In a specific embodiment, the raised sections 321 of the second weld 32 and the fourth weld 34 are the main raised portions. Compared with the raised portion of one weld, the two raised portions disperse the overall excess height of the molten pool, and the stress accumulation is weakened, thereby increasing the weld strength.

[0062] Furthermore, the width h of the linear weld satisfies the relationship 40μm<h<50μm. When 40μm<h<50μm, the weld width is moderate and will not significantly reduce the rigidity of the tab assembly 20 and the shell 10. The weld strength is high and it is not likely to cause the tab assembly 20 or the shell 10 to separate from each other when subjected to external forces. The value of h can be 41μm, 42μm, 43μm, 44μm, 45μm, 46μm, 47μm, 48μm, and 49μm. When h is less than or equal to 40μm, the weld width is small, the weld strength is low, and the connection between the tab assembly 20 and the shell 10 is not secure. When h is greater than or equal to 50μm, the weld width is too large, reducing the rigidity of the tab assembly 20 and the shell 10. In addition, when welding multiple linear welds, the width h of each linear weld is affected by the distance between adjacent welds, that is, the effect of heat accumulation. When h is less than or equal to 40 μm, the heat accumulation is too large and the welding effect is poor. When h is greater than or equal to 50 μm, there is no heat accumulation effect.

[0063] Furthermore, the length D of the linear weld and the width M of the tab assembly 20 satisfy the relationship 60% ≤ D / M ≤ 70%. For example, the value of D / M can be 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, and 70%. Within the above range, the weld length is moderate and the weld strength is moderate. When D / M is less than 60%, the weld length is too short and the weld strength is insufficient. When D / M is greater than 70%, the weld length is too long and it is easy to melt to the edge of the tab assembly 20, damaging the tab assembly 20.

[0064] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used herein to describe the spatial positional relationship of a device or feature to other devices or features as shown in the figures. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figures. For example, if the device in the drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0065] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of this application.

[0066] The above are merely preferred embodiments of the present application and are not intended to limit the present application. Those skilled in the art will readily appreciate that various modifications and variations are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A battery, characterized in that: include: A housing (10), wherein a receiving cavity is provided on the housing (10), and the housing (10) has a first side wall (11); A battery cell (40), the battery cell (40) being arranged in the accommodating cavity, and the battery cell (40) comprising a tab assembly (20); The tab assembly (20) is welded to the first side wall (11) by at least two linear welds, and the at least two linear welds are arranged in sequence along a first direction. One end of the linear weld close to the first side wall (11) is penetrated into the first side wall (11), and along the wall thickness direction of the first side wall (11), the ends of two adjacent linear welds penetrated into the first side wall (11) are arranged at different heights.

2. The battery according to claim 1, characterized in that The number of the linear welds is greater than or equal to 3 and less than or equal to 5.

3. The battery according to claim 1, characterized in that The linear weld includes a first weld (31), a second weld (32), a third weld (33), a fourth weld (34) and a fifth weld (35) which are sequentially arranged along the first direction, and the first weld (31), the second weld (32), the third weld (33), the fourth weld (34) and the fifth weld (35) are arranged in a staggered manner along the thickness direction of the first side wall (11).

4. The battery according to claim 3, characterized in that The penetration depth of the second weld (32) into the first side wall (11) is greater than the penetration depth of the first weld (31), the third weld (33), the fourth weld (34) and the fifth weld (35) into the first side wall (11); and / or, The depth to which the third weld (33) penetrates into the first side wall (11) is the same as the depth to which the fifth weld (35) penetrates into the first side wall (11); and / or, The depth to which the first weld (31) penetrates into the first side wall (11) is the same as the depth to which the fourth weld (34) penetrates into the first side wall (11); and / or, The depths to which the first weld (31) and the fourth weld (34) penetrate into the first side wall (11) are greater than the depths to which the third weld (33) and the fifth weld (35) penetrate into the first side wall (11).

5. The battery according to claim 3, characterized in that Along the first direction, the sum H of the widths of the first weld (31), the second weld (32), the third weld (33), the fourth weld (34) and the fifth weld (35) satisfies the relationship 170 μm<H<220 μm.

6. The battery according to claim 3, characterized in that The tab assembly (20) comprises a first surface (21) facing away from the first side wall (11); a first wave valley (311) is provided between the first weld (31) and the second weld (32); a second wave valley (312) is provided between the second weld (32) and the third weld (33); a third wave valley (313) is provided between the third weld (33) and the fourth weld (34); and a fourth wave valley (314) is provided between the fourth weld (34) and the fifth weld (35); Wherein, along the thickness direction of the first side wall (11), the vertical distance from the third wave valley (313) to the first surface (21) is greater than the vertical distances from the first wave valley (311), the second wave valley (312) and the fourth wave valley (314) to the first surface (21); and / or, The vertical distance from the second wave valley (312) to the first surface (21) is smaller than the vertical distances from the first wave valley (311) and the fourth wave valley (314) to the first surface (21); and / or, A vertical distance from the first wave valley (311) to the first surface (21) is greater than a vertical distance from the fourth wave valley (314) to the first surface (21).

7. The battery according to claim 6, characterized in that Along the first direction, among two adjacent troughs, the vertical distance between the third trough (313) and the fourth trough (314) is greater than the vertical distance between the other two adjacent troughs, and the vertical distance between the second trough (312) and the third trough (313) is less than the vertical distance between the other two adjacent troughs.

8. The battery according to claim 6, characterized in that The first weld (31) includes a first wave peak (301), the second weld (32) includes a second wave peak (302), the third weld (33) includes a third wave peak (303), the fourth weld (34) includes a fourth wave peak (304), and the fifth weld (35) includes a fifth wave peak (305); Wherein, along the first direction, of two adjacent wave peaks, the vertical distance between the second wave peak (302) and the third wave peak (303) is greater than the vertical distance between the remaining two adjacent wave peaks; and / or, The vertical distance between the fourth wave crest (304) and the fifth wave crest (305) is smaller than the vertical distance between the other two adjacent wave crests; and / or, A vertical distance between the first wave peak (301) and the second wave peak (302) is greater than a vertical distance between the third wave peak (303) and the fourth wave peak (304).

9. The battery according to any one of claims 1 to 8, characterized in that The maximum depth Kmax of the linear weld penetrating into the first side wall (11) and the thickness J of the first side wall (11) satisfy the relationship 50%≤Kmax / J≤90%.

10. The battery according to any one of claims 1 to 8, characterized in that The linear weld comprises a raised section (321), the raised section (321) protruding from a surface of the tab assembly (20) facing away from the first side wall (11), and a height W of the raised section (321) satisfies the relationship 20 μm<W<30 μm.

11. The battery according to any one of claims 1 to 8, characterized in that The width h of the linear weld satisfies the relationship 40 μm<h<50 μm.

12. The battery according to any one of claims 1 to 8, characterized in that The length D of the linear weld and the width M of the tab assembly (20) satisfy the relationship of 60%≤D / M≤70%.

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