Battery and battery pack

Abstract

The present invention relates to the technical field of batteries, and discloses a battery and a battery pack, the battery comprises: a terminal structure having a welding surface attached to and welded to a busbar to form a welding mark; the capacity of the battery is A, the charge-discharge rate of the battery is C, the overcurrent capacity of a welding mark passing current is K, the current passing area needed by the battery is S, the effective area of the welding mark is S0, and the requirement of # imgabs0 is met. The effective area of the welding mark cannot be smaller than the current passing area needed by the battery in order to guarantee the overcurrent capacity of the welding mark. A certain safety margin can be set for the effective area of the welding mark, so that the welding mark is further ensured to have enough overcurrent capability, the welding failure caused by the fact that the welding mark exceeds the welding surface of the terminal structure during welding due to the overlarge effective area of the welding mark is avoided, and the welding failure caused by the overlarge area of the required welding surface due to the overlarge effective area of the welding mark is also avoided. And the size of the terminal structure is too large, so that the overall weight of the battery is too large.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to batteries and battery packs. Background Art

[0002] A battery pack typically includes multiple batteries arranged side by side and / or stacked. The terminal structure of each battery is welded to a busbar, which allows the multiple batteries to be connected in series or in parallel through the busbar, thereby realizing the charge and discharge functions of the entire battery pack. The battery terminal structure serves to connect the inside and outside of the battery, providing a channel for bidirectional current transmission during charging and discharging. Therefore, it is necessary to ensure that the welds between the terminal structure and the busbar have sufficient current transmission paths to ensure overcurrent capability. However, the increase in the current transmission path will increase the size of the required terminal structure, resulting in an increase in the overall weight of the battery. Summary of the Invention

[0003] In view of this, the present invention provides a battery and a battery pack to solve the problem in the prior art that the battery terminal structure cannot take into account both overcurrent capability and lightweight design.

[0004] In a first aspect, the present invention provides a battery comprising: a terminal structure having a welding surface, the welding surface being adapted to be attached to and welded to a busbar to form a weld mark; wherein the capacity of the battery is A, the maximum charge and discharge rate of the battery is C, the current flow capacity of the weld mark is K, the current flow area required by the battery is S, the effective area of the weld mark is S0, and the battery is provided with: The unit of A is Ah, the unit of C is 1 / h, and the unit of K is A / mm 2 , the unit of S is mm 2 , the unit of S0 is mm 2 .

[0005] Beneficial effect: In order to ensure the overcurrent capacity of the weld mark, the effective area of the weld mark cannot be less than the current flow area required by the battery, and a certain safety margin can be set for the effective area of the weld mark. While further ensuring that the weld mark has sufficient overcurrent capacity, it avoids the effective area of the weld mark being too large, which may cause the weld mark to exceed the welding surface of the terminal structure during welding and cause welding failure. It also avoids the effective area of the weld mark being too large, which may cause the area of the required welding surface to be too large, thereby causing the terminal structure to be too large and the overall weight of the battery to be too large.

[0006] In an optional embodiment, the effective length of the weld mark is P, the effective weld width of the weld mark is W0, and the number of weld marks is n, satisfying S0=P×W0×n, where P is in mm, W0 is in mm, and n is a positive integer.

[0007] In an optional embodiment, when the weld mark is a strip structure, the effective length of the weld mark is the total length of the weld mark; or, when the weld mark is a ring structure, the effective length of the weld mark is the circumference of the ring structure at the midpoint of the effective weld width of the weld mark.

[0008] In an optional embodiment, the effective length P of the weld mark satisfies 10 mm ≤ P ≤ 100 mm; and / or the effective weld width W0 of the weld mark satisfies 1.0 mm ≤ W0 ≤ 5.0 mm.

[0009] In an optional embodiment, the area of the welding surface is S1, which satisfies The unit of S1 is mm 2 .

[0010] Beneficial effect: While ensuring that the welding surface has sufficient area to fully accommodate the weld mark, it avoids the terminal structure being too large due to the welding surface area being too large, thereby meeting the lightweight design of the battery.

[0011] In an optional embodiment, along the penetration direction of the weld mark, the thickness of the terminal structure at the position of the weld mark is t, and t≥1.5 mm.

[0012] Beneficial effect: ensuring that the terminal structure is thick enough to accommodate the penetration of the weld mark, preventing the weld mark from penetrating the terminal structure, thereby avoiding ablation of components around the terminal structure.

[0013] In an optional embodiment, the minimum distance between the outer edge of the weld mark and the edge of the weld surface is a, satisfying a≥1 mm.

[0014] Beneficial effect: A certain safety distance is reserved between the outer edge of the weld mark and the edge of the welding surface to avoid welding slag splashing and / or the weld mark exceeding the edge of the terminal structure, causing ablation of components around the terminal structure.

[0015] In an optional embodiment, the terminal structure includes a pole and a connecting block, the pole is inserted into the connecting block, the pole and the connecting block are welded to form a welding area, the weld mark is located on the connecting block, and the minimum distance between the welding area and the weld mark is b, satisfying b≥1mm.

[0016] Beneficial effect: A certain safety distance is reserved between the welding area and the weld mark to avoid the welding area and the weld mark overlapping and causing welding problems such as weld penetration.

[0017] In an optional embodiment, the maximum charge and discharge rate C of the battery satisfies 1≤C≤10.

[0018] In a second aspect, the present invention further provides a battery pack comprising the above-mentioned battery, wherein a plurality of the batteries are provided, and the battery pack further comprises a bus bar, which is welded to the terminal structures of two of the batteries at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0020] Figure 1 A top view of a first battery according to an embodiment of the present invention;

[0021] Figure 2 is a top view of a second battery according to an embodiment of the present invention;

[0022] Figure 3 is a top view of a third battery according to an embodiment of the present invention;

[0023] Figure 4 for Figure 3 Cross-sectional view in the AA direction;

[0024] Figure 5 is a top view of a fourth battery according to an embodiment of the present invention;

[0025] Figure 6 for Figure 5 Cross-sectional view in the middle BB direction;

[0026] Figure 7 Schematic diagram of the welding structure of the busbar and the terminal structure according to an embodiment of the present invention;

[0027] Figure 8 This is a structural diagram of a circular ring structure weld print according to an embodiment of the present invention;

[0028] Figure 9 Schematic diagram of the structure of the rectangular ring structure weld print according to an embodiment of the present invention.

[0029] Description of reference numerals:

[0030] 1. Terminal structure; 11. Welding surface; 12. Pole; 13. Connection block; 2. Busbar; 3. Welding mark; 4. Cover plate. DETAILED DESCRIPTION

[0031] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative efforts shall fall within the scope of protection of the present invention.

[0032] The following combination Figures 1 to 9 , describing embodiments of the present invention.

[0033] According to an embodiment of the present invention, on the one hand, a battery is provided, comprising: a terminal structure 1 having a welding surface 11, the welding surface 11 being adapted to be attached to and welded with a busbar 2 to form a weld mark 3; wherein the capacity of the battery is A, the maximum charge and discharge rate of the battery is C, the current flow capacity of the weld mark 3 is K, the current flow area required by the battery is S, the effective area of the weld mark 3 is S0, and the battery is provided with: The unit of A is Ah, the unit of C is 1 / h, and the unit of K is A / mm 2 , the unit of S is mm 2 , the unit of S0 is mm 2 .

[0034] In order to ensure the overcurrent capacity of the weld mark 3, the effective area of the weld mark 3 cannot be smaller than the current passing area required by the battery, and a certain safety margin can be set for the effective area of the weld mark 3. While further ensuring that the weld mark 3 has sufficient overcurrent capacity, it can also avoid the effective area of the weld mark 3 being too large, which may cause the weld mark 3 to exceed the welding surface 11 of the terminal structure 1 during welding and cause welding failure. It can also avoid the effective area of the weld mark 3 being too large, which may cause the area of the required welding surface 11 to be too large, thereby causing the size of the terminal structure 1 to be too large and the overall weight of the battery to be too large.

[0035] It is worth noting that the current flow area S required by the battery is the minimum effective area of the weld mark 3 that meets the overcurrent capability of the battery, that is, the effective area S0 of the weld mark 3 needs to be at least S, that is, it is necessary to make S0 ≥ S; however, when the effective area S0 of the weld mark 3 is larger, the area of the welding surface 11 needs to be larger in order to accommodate the weld mark 3, which will lead to a larger size of the terminal structure 1, and further lead to a larger overall weight of the battery, which is not conducive to the lightweight design of the battery. Therefore, in this embodiment, the current flow area S required by the battery and the effective area S0 of the weld mark 3 are made to meet That is, S≤S0≤1.3S, taking into account both the overcurrent capability of the terminal structure 1 and the lightweight design of the battery.

[0036] It should be further explained that the area S through which the current passes that the battery requires is related to the battery's own parameters (the battery's capacity A, the battery's maximum charge and discharge rate C, and the current flow capacity K of the weld mark 3). Battery capacity is one of the important performance indicators for measuring battery performance. It indicates the amount of electricity discharged by the battery under certain conditions (discharge rate, temperature, termination voltage, etc.). The capacity of the battery is usually related to the amount of active material in the battery and the utilization rate of the active material. The more active material there is, the higher the utilization rate of the active material, and the greater the capacity of the battery. The charge and discharge rate of the battery refers to the current value required for the battery to discharge its rated capacity within a specified time. In terms of data value, it is equal to a multiple of the battery's rated capacity, that is, the charge and discharge rate = charge and discharge current / rated capacity. The current flow capacity K of the weld mark 3 is related to the material of the terminal structure 1. For example, for a terminal structure 1 made of aluminum, the current flow capacity K of the weld mark 3 is 8A / mm. 2 .

[0037] It is worth noting that the battery of this embodiment can be a battery of various structural forms, such as a prismatic battery, a blade battery, a cylindrical battery, etc. The larger the battery capacity, the greater the current passing through the terminal structure 1 per unit time. Therefore, the weld 3 connecting the terminal structure 1 and the busbar 2 requires a larger current flow area to provide a larger current transmission path.

[0038] Furthermore, the maximum charge and discharge rate C of the battery satisfies 1≤C≤10.

[0039] In one embodiment, the effective welding area S0 of the weld mark 3 can be calculated based on the effective length of the weld mark 3, the effective weld width of the weld mark 3, and the number of weld marks 3. Specifically, the effective length of the weld mark 3 is P, the effective weld width of the weld mark 3 is W0, and the number of weld marks 3 is n, satisfying S0=P×W0×n, where P is in mm, W0 is in mm, and n is a positive integer.

[0040] It is worth noting that if Figure 7 As shown, the effective weld width of weld mark 3 is the weld width corresponding to the joint between the welding surface 11 of the terminal structure 1 and the busbar 2. The effective weld width of weld mark 3 can be obtained by metallographically measuring the cross section of the terminal structure 1 and the busbar 2 at weld mark 3.

[0041] Further, such as Figures 1 to 9 As shown, the shape of the weld mark 3 can be a strip structure or an annular structure (such as a circular ring, a rectangular ring, etc.). When the weld mark 3 is a strip structure, the effective length of the weld mark 3 is the total length of the weld mark 3; when the weld mark 3 is an annular structure, the effective length of the weld mark 3 is the circumference of the annular structure at the midpoint of the effective weld width of the weld mark 3.

[0042] Specifically, such as Figure 2As shown, the weld mark 3 is a strip structure, and the effective length P of the weld mark 3 is equal to the length L of the weld mark 3, that is, P = L. Figure 8 As shown, the weld mark 3 is a circular ring structure, the inner radius of the circular ring structure is r, and the effective length of the weld mark 3 is P = 2×π×(r+W0 / 2). Figure 9 As shown, the weld mark 3 is a rectangular ring structure, the inner circle length of the rectangular ring structure is L1, and the width is L2. The effective length P of the weld mark 3 is 2×(L1+W0)+2×(L2+W0).

[0043] It is worth noting that the welding mark 3 can be set to one or more, that is, n=1, or n=2, or n=3... and so on.

[0044] In one embodiment, the effective length P of the weld mark 3 satisfies 10 mm ≤ P ≤ 100 mm.

[0045] In one embodiment, due to the influence of factors such as welding parameters and thickness differences of the busbar 2 , the actual width of the weld mark 3 may fluctuate to a certain extent, and the effective weld width W0 of the weld mark 3 satisfies 1.0 mm ≤ W0 ≤ 5.0 mm.

[0046] In one embodiment, the area of the welding surface 11 is S1, which satisfies The unit of S1 is mm 2 This arrangement ensures that the welding surface 11 has a sufficient area to fully accommodate the welding mark 3 while avoiding the terminal structure 1 being too large due to the area of the welding surface 11 being too large, thereby meeting the lightweight design of the battery.

[0047] It is worth noting that if If the value is too small, during actual welding, the welding surface 11 of the terminal structure 1 cannot accommodate all the weld marks 3, or the weld marks 3 may be offset in position and / or have size deviations, which may cause the weld marks 3 to exceed the welding surface 11 of the terminal structure 1, resulting in poor welding and erosion of parts around the terminal structure 1. If the value of is too large, the area of the welding surface 11 will be too large, which will lead to an excessive size of the terminal structure 1 and an excessive weight of the battery.

[0048] It should be noted that the terminal structure 1 is typically in the form of a circular cylinder or a square cylinder, so that the welding surface 11 is typically a circular surface or a square surface, and the area of the welding surface 11 is the area of the circular surface or the area of the square surface. Of course, the terminal structure 1 can also have other regular or irregular shapes. The surface of the terminal structure 1 used for welding to the busbar 2 is the welding surface 11. After determining the welding surface 11, the area of the welding surface 11 can be calculated based on the shape of the welding surface 11.

[0049] In one embodiment, Figure 4、 Figure 6 and Figure 7 As shown, the thickness of the terminal structure 1 at the weld mark 3 along the direction of weld penetration is t, satisfying t ≥ 1.5 mm. This configuration ensures that the terminal structure 1 is thick enough to accommodate the weld penetration of the weld mark 3, preventing the weld mark 3 from penetrating the terminal structure 1 and thus preventing ablation of components surrounding the terminal structure 1.

[0050] It is worth noting that in order to ensure the welding strength of the terminal structure 1 and the busbar 2, it is necessary to ensure that the weld mark 3 has a certain welding penetration. If the thickness of the terminal structure 1 at the weld mark 3 is too small, the weld mark 3 may easily penetrate the terminal structure 1 in the penetration direction, which may easily cause erosion of the peripheral components of the terminal structure 1.

[0051] It should be noted that the thickness of the terminal structure 1 at least at the position of the weld mark 3 is t, and the thickness of the terminal structure 1 at other positions can also be t. Of course, it can also be greater than t or less than t. The specific situation can be set according to actual design needs.

[0052] In one embodiment, Figures 1 to 3 as well as Figure 5 As shown, the minimum distance a between the outer edge of the weld mark 3 and the edge of the welding surface 11 satisfies a ≥ 1 mm. This arrangement leaves a safe distance between the outer edge of the weld mark 3 and the edge of the welding surface 11, preventing welding slag from splashing and / or the weld mark 3 from extending beyond the edge of the terminal structure 1, which could cause ablation of components surrounding the terminal structure 1.

[0053] It is worth noting that the terminal structure 1 and the bus 2 are laser welded, and the laser of the welding equipment is usually applied to the terminal structure 1 through a protective copper nozzle. If the distance between the outer edge of the weld mark 3 and the edge of the welding surface 11 is too small, the welding slag during the welding process will easily splash onto the surrounding components of the terminal structure 1, and the weld mark 3 will easily exceed the edge of the welding surface 11, causing the surrounding components of the terminal structure 1 to be burned.

[0054] In one embodiment, Figures 1 to 3 As shown, the terminal structure 1 includes a pole 12 and a connecting block 13. The pole 12 is inserted into the connecting block 13. The pole 12 and the connecting block 13 are welded to form a weld zone. The weld mark 3 is located on the connecting block 13. The minimum distance between the weld zone and the weld mark 3 is b, and b ≥ 1 mm. This arrangement reserves a certain safety distance between the weld zone and the weld mark 3 to prevent the weld zone and the weld mark 3 from overlapping and causing welding problems such as weld penetration.

[0055] It is worth noting that when welding is present between the pole 12 and the connecting block 13 as well as between the connecting block 13 and the busbar 2, if the distance between the welding area formed by welding the pole 12 and the connecting block 13 and the weld mark 3 formed by welding the connecting block 13 and the busbar 2 is too small, the welding area and the weld mark 3 may overlap due to inaccurate positioning of the welding equipment, which may easily lead to welding defects such as weld penetration.

[0056] Furthermore, when the weld mark 3 is located on the connecting block 13, the surface of the connecting block 13 forms a welding surface 11, the edge of the welding surface 11 is the edge of the connecting block 13, and the minimum distance a between the outer edge of the weld mark 3 and the edge of the welding surface 11 is the minimum distance between the edge of the weld mark 3 and the edge of the connecting block 13.

[0057] Of course, in other alternative embodiments, such as Figure 5 As shown, the terminal structure 1 includes a pole 12, and the weld mark 3 is located on the pole 12. At this time, the end surface of the pole 12 forms the welding surface 11, the edge of the welding surface 11 is the edge of the pole 12, and the minimum distance a between the outer edge of the weld mark 3 and the edge of the welding surface 11 is the minimum distance between the edge of the weld mark 3 and the edge of the pole 12.

[0058] It should be noted that the battery further includes a cover plate 4 and a shell. At least one end of the shell is open. The cover plate 4 is connected to the shell and blocks the opening. The terminal structure 1 is provided on the cover plate 4 and / or the shell.

[0059] The actual overcurrent capabilities of batteries and busbars 2 with different terminal structures 1 and weld marks 3 were tested and evaluated below. The test results for the example batteries are shown in Table 1, and the test results for the comparative example batteries are shown in Table 2. The example batteries refer to batteries that meet the requirements of this example, while the comparative example batteries refer to batteries that do not meet the requirements of this example.

[0060] Table 1 Example battery test results

[0061]

[0062] Table 2 Comparative Example Battery Test Results

[0063]

[0064] It can be seen from Table 1 that in Examples 1 to 7, the current passing area S required by the battery and the effective area S0 of the weld mark 3 meet The weld mark 3 can meet the use requirements of the current; at the same time, the effective area S0 of the weld mark 3 and the area S1 of the welding surface 11 meet The weld mark 3 can be completely arranged within the weld surface 11; and the terminal structure 1 has an appropriate size, so that the battery can meet the lightweight design requirements.

[0065] Comparing Table 2 with Table 1, it can be concluded that, compared with Example 1, the effective length P of the weld mark 3 in Comparative Example 1 is larger, and accordingly, the effective area S0 of the weld mark 3 is also larger, while the capacity A of the battery and the maximum charge and discharge rate C of the battery do not change. Therefore, the value of the current passing through the area S required by the battery does not change, resulting in The value of is greater than 1.3, which makes the flow capacity of the weld mark 3 too much. However, since the area S1 of the weld surface 11 does not change, The value of is less than 1.2, which causes fluctuations in laser positioning during actual welding, resulting in weld mark 3 melting the protective plastic and affecting the insulation performance.

[0066] Comparing Table 2 with Table 1, it can be concluded that the value of the maximum charge and discharge rate C of the battery in Comparative Example 2 is larger than that in Example 2. Accordingly, the value of the current passing area S required by the battery is also larger, while the values of the effective length P of the weld mark 3, the effective weld width W0 of the weld mark 3, and the number n of the weld marks 3 remain unchanged. Therefore, the value of the effective area S0 of the weld mark 3 remains unchanged, resulting in The value of is less than 1, which makes the effective area of the weld mark 3 too small to meet the overcurrent requirement, resulting in the temperature of the connection block 13 being too high, exceeding 60°C, and there is a risk of thermal runaway.

[0067] Comparing Table 2 with Table 1, it can be concluded that in Comparative Example 3, the effective weld width W0 of weld mark 3 is larger than that of Example 3. Accordingly, the effective area S0 of weld mark 3 is also larger, while the capacity A of the battery and the maximum charge and discharge rate C of the battery remain unchanged. Therefore, the current required by the battery to pass through the area S remains unchanged, resulting in The value of is greater than 1.3, which makes the flow capacity of the weld mark 3 too much; and since the value of the area S1 of the weld surface 11 does not change, The value of is less than 1.2, which causes fluctuations in laser positioning during actual welding, resulting in weld mark 3 melting the protective plastic and affecting the insulation performance.

[0068] Comparing Table 2 with Table 1, it can be concluded that in Comparative Example 4, the effective weld width W0 of weld mark 3 is smaller than that of Example 4. Accordingly, the effective area S0 of weld mark 3 is also smaller, while the capacity A of the battery and the maximum charge and discharge rate C of the battery remain unchanged. Therefore, the current required by the battery to pass through the area S remains unchanged, resulting in The value of is less than 1, which makes the effective area of the weld mark 3 too small to meet the overcurrent requirement, resulting in the temperature of the connection block 13 being too high, exceeding 60°C, and there is a risk of thermal runaway.

[0069] Comparing Table 2 with Table 1, it can be concluded that the value of the battery capacity A in Comparative Example 5 is smaller than that in Example 5. Accordingly, the value of the current passing area S required by the battery is also smaller, while the values of the effective length P of the weld mark 3, the effective weld width W0 of the weld mark 3, and the number n of the weld marks 3 remain unchanged. Therefore, the value of the effective area S0 of the weld mark 3 remains unchanged, resulting in The value of is greater than 1.3, which makes the flow capacity of welding mark 3 too redundant, resulting in reduced welding efficiency and waste of production resources.

[0070] Comparing Table 2 with Table 1, it can be concluded that in Comparative Example 6, the effective length P of the weld mark 3 is smaller than that in Example 6. Accordingly, the effective area S0 of the weld mark 3 is also smaller, while the capacity A of the battery and the maximum charge and discharge rate C of the battery remain unchanged. Therefore, the current required by the battery to pass through the area S remains unchanged, resulting in The value of is less than 1, which makes the effective area of the weld mark 3 too small to meet the overcurrent requirement, resulting in the temperature of the connection block 13 being too high, exceeding 60°C, and there is a risk of thermal runaway.

[0071] Comparing Table 2 with Table 1, it can be concluded that the value of the battery capacity A in Comparative Example 7 is larger than that in Example 7. Accordingly, the value of the current passing area S required by the battery is also larger, while the effective length P of the weld mark 3, the effective weld width W0 of the weld mark 3, and the number n of the weld marks 3 remain unchanged. Therefore, the value of the effective area S0 of the weld mark 3 remains unchanged, resulting in The value of is less than 1, which makes the effective area of the weld mark 3 too small to meet the overcurrent requirement, resulting in the temperature of the connection block 13 being too high, exceeding 60°C, and there is a risk of thermal runaway.

[0072] According to an embodiment of the present invention, on the other hand, a battery pack is provided, including the above-mentioned battery, wherein a plurality of batteries are provided, and the battery pack further includes a busbar 2, which is welded to the terminal structures 1 of two batteries at the same time.

[0073] Although the embodiments of the present invention have been described with reference to the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention. Such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A battery, characterized in that: include: A terminal structure having a welding surface, wherein the welding surface is adapted to be attached to and welded to the busbar to form a weld mark; Among them, the capacity of the battery is A, the maximum charge and discharge rate of the battery is C, the current capacity of the weld print is K, the current passing area required by the battery is S, and the effective area of the weld print is S0, satisfying The unit of A is Ah, the unit of C is 1 / h, and the unit of K is A / mm 2 , the unit of S is mm 2 , the unit of S0 is mm 2 .

2. The battery according to claim 1, characterized in that The effective length of the weld mark is P, the effective weld width of the weld mark is W0, the number of the weld marks is n, and S0=P×W0×n is satisfied, where the unit of P is mm, the unit of W0 is mm, and n is a positive integer.

3. The battery according to claim 2, characterized in that When the weld mark is a strip structure, the effective length of the weld mark is the total length of the weld mark; or When the weld mark is an annular structure, the effective length of the weld mark is the circumference of the annular structure at the midpoint of the effective weld width of the weld mark.

4. The battery according to claim 2, characterized in that The effective length P of the weld mark satisfies 10 mm ≤ P ≤ 100 mm; and / or, The effective weld width W0 of the weld mark satisfies 1.0 mm ≤ W0 ≤ 5.0 mm.

5. The battery according to any one of claims 1 to 4, characterized in that The area of the welding surface is S1, which satisfies The unit of S1 is mm 2 .

6. The battery according to any one of claims 1 to 4, characterized in that Along the penetration direction of the weld mark, the thickness of the terminal structure at the position of the weld mark is t, and t≥1.5 mm.

7. The battery according to any one of claims 1 to 4, characterized in that The minimum distance between the outer edge of the weld mark and the edge of the weld surface is a, satisfying a≥1mm.

8. The battery according to any one of claims 1 to 4, characterized in that The terminal structure includes a pole and a connecting block, the pole is inserted into the connecting block, the pole and the connecting block are welded to form a welding area, the weld mark is located on the connecting block, and the minimum distance between the welding area and the weld mark is b, satisfying b≥1mm.

9. The battery according to any one of claims 1 to 4, characterized in that The maximum charge and discharge rate C of the battery satisfies 1≤C≤10.

10. A battery pack, characterized in that: The battery according to any one of claims 1 to 9 is provided in plurality, and the battery pack further comprises a bus bar, which is welded to the terminal structures of two of the batteries at the same time.

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