Battery cap and battery

Abstract

The invention relates to the technical field of batteries, in particular to a battery cap and a battery. The battery cap comprises a top cover and a pressure relief piece, the pressure relief piece is arranged on the side, facing the interior of a battery, of the top cover, a wrapping part extending towards the top cover is formed on the circumferential edge of the pressure relief piece, the wrapping part is arranged on the circumferential edge of the top cover in a surrounding mode, the wrapping part is connected with part of the edge of the top cover in a welded mode to form a welding part, the effective penetration of the welding part is h, and the effective penetration of the welding part is h. The effective fusion width w of the welding part is larger than or equal to 0.45 mm and smaller than or equal to 1.5 mm; and in the axial direction of the battery cap, the height size of the coating part is H, and h / H is more than or equal to 0.8 and less than or equal to 1.2. According to the invention, under the condition of reliable welding strength, the internal resistance electrical performance can be prevented from being influenced by an overlarge effective melting width or h / H parameter, so that the output power and performance of the battery are ensured, the thermal runaway risk of the battery is reduced, and the safety performance and the service life of the battery are improved.

Description

Technical Field

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

[0002] Lithium batteries have the advantages of light weight, high energy density, high power, and long service life, and are widely used in fields such as two-wheel vehicles, energy storage base stations, and new energy vehicles. The cap of the battery and the housing of the battery enclose a sealed space for assembling the electrode group. The cap includes a top cover, a hole plate, an insulating ring, a sealing ring, and an explosion-proof valve. In the existing structure, the top cover and the explosion-proof valve are fixed by welding, and the welding position is on the outer surface of the top cover. The welding molten pool passes through the top cover to realize the connection between the top cover and the explosion-proof valve. The welding temperature and duration are relatively high, resulting in an increase in internal resistance after welding, thereby reducing the output power and efficiency of the battery, prolonging the charging and discharging time, and the increase in internal resistance may also cause the battery to overheat, increasing the risk of thermal runaway and affecting the use performance and life of the battery. Summary of the Invention

[0003] In view of this, the purpose of this application is to provide a battery cap and a battery to solve the problem that the welding position between the top cover and the explosion-proof valve in the existing battery cap is on the outer surface of the top cover, resulting in an increase in internal resistance after welding and affecting the output power, performance, and life of the battery.

[0004] The first aspect of the present invention provides a battery cap, which includes:

[0005] A top cover;

[0006] A pressure relief member disposed on the side of the top cover facing the inside of the battery. A covering portion extending toward the top cover is formed on the circumferential edge of the pressure relief member. The covering portion surrounds the circumferential edge of the top cover, and the covering portion and a partial edge of the top cover are welded and connected to form a welding portion. The effective penetration depth of the welding portion is h, and the effective penetration width of the welding portion is w, where 0.45 mm ≤ w ≤ 1.5 mm;

[0007] In the axial direction of the battery cap, the height dimension of the covering portion is H, and 0.8 ≤ h / H ≤ 1.2.

[0008] Preferably, 0.3 mm ≤ H ≤ 1.15 mm.

[0009] Preferably, the surface of the top cover facing the outside of the battery protrudes from the end of the covering portion facing the outside of the battery, so that in the axial direction of the battery cap, a height difference L is formed between the top cover and the covering portion, where 0.05 mm ≤ L ≤ 0.2 mm.

[0010] Preferably, in the axial direction of the battery cap, the thickness dimension of the top cover is K, where 0.5 mm ≤ K ≤ 1.2 mm.

[0011] Preferably, the welding part is formed into an arc-shaped structure, the total arc length dimension of the welding part is S1, the length of the circumferential edge of the top cover is S0, and 0.30 ≤ S1 / S0 ≤ 0.65.

[0012] Preferably, a plurality of the welding parts are provided, and the plurality of welding parts are distributed at equal intervals around the top cover.

[0013] Preferably, the welding part is formed into an arc-shaped structure, and the center of the welding part is arranged on the axis of the battery cap.

[0014] Preferably, it further includes:

[0015] A seal, which is arranged around the circumferential edge of the pressure relief part. One end of the seal facing the outside of the battery is formed into a flanging part protruding from the top cover. The flanging part is bent to be crimped with the top cover to cover the welding part.

[0016] Preferably, the flanging part is formed into an annular structure, a convex part is formed on the inner circumferential wall of the flanging part, and the flanging part is bent so that the convex part is crimped with the covering part and at least part of the welding part.

[0017] The second aspect of the present invention provides a battery, including the battery cap according to any one of the above technical solutions.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0019] In the battery cap of the present invention, a covering part extending towards the top cover is formed on the circumferential edge of the pressure relief part. The covering part is arranged around the circumferential edge of the top cover, and the covering part and part of the edge of the top cover are welded and connected to form a welding part. In this way, the welding part is arranged between the top cover and the pressure relief part, which reduces the influence of the welding part on the internal resistance to a certain extent. The effective penetration depth of the welding part is h, and the effective penetration width of the welding part is w, 0.45 mm ≤ w ≤ 1.5 mm. In the axial direction of the battery cap, the height dimension of the covering part is H, and 0.8 ≤ h / H ≤ 1.2. In this way, while ensuring reliable welding strength, it can also avoid the parameters of the effective penetration width or h / H being too large and affecting the internal resistance electrical performance, thereby ensuring the output power and performance of the battery, reducing the risk of battery thermal runaway, and improving the safety performance and service life of the battery.

[0020] In order to make the above objects, features and advantages of the present application more obvious and understandable, the following specifically enumerates preferred embodiments and, in conjunction with the accompanying drawings, is described in detail as follows. Description of the Drawings

[0021] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0022] Figure 1 Structural schematic diagram of the battery cap provided by an embodiment of the present invention;

[0023] Figure 2 Structural sectional view of the battery cap provided by an embodiment of the present invention;

[0024] Figure 3 For Figure 2 Enlarged structural schematic diagram at A in

[0025] Reference numerals: 10 - top cover; 20 - pressure relief member; 21 - covering portion; 30 - welding portion; 40 - seal; 41 - flanging portion; 401 - convex portion. Specific embodiments

[0026] The following specific embodiments are provided to assist the reader in obtaining a comprehensive understanding of the methods, devices, and / or systems described herein. However, after understanding the disclosure of the present application, various changes, modifications, and equivalents of the methods, devices, and / or systems described herein will be apparent. For example, the order of operations described herein is merely illustrative and is not limited to the order set forth herein. Rather, changes that will be apparent after understanding the disclosure of the present application can be made, except for operations that must occur in a specific order. In addition, descriptions of features known in the art may be omitted for the sake of clarity and conciseness.

[0027] The features described herein may be implemented in different forms and should not be construed as limited to the examples described herein. Rather, the examples described herein are provided only to illustrate some of the many possible ways of implementing the methods, devices, and / or systems described herein that will be apparent after understanding the disclosure of the present application.

[0028] Throughout the specification, when an element such as a layer, region, or substrate is described as being "on" another element, "connected to" another element, "coupled to" another element, "above" another element, or "covering" another element, it can be directly "on" the other element, "connected to" the other element, "coupled to" the other element, "above" the other element, or "covering" the other element, or there can be one or more other elements intervening between them. In contrast, when an element is described as being "directly on" another element, "directly connected to" another element, "directly coupled to" another element, "directly above" another element, or "directly covering" another element, there can be no other elements intervening between them.

[0029] As used herein, the term "and / or" includes any one of the listed related items and any combination of any two or more of them.

[0030] Although terms such as "first", "second", and "third" may be used herein to describe various components, elements, regions, layers, or parts, these components, elements, regions, layers, or parts are not limited by these terms. Rather, these terms are only used to distinguish one component, element, region, layer, or part from another. Thus, a first component, element, region, layer, or part so-called in the examples described herein may also be referred to as a second component, element, region, layer, or part without departing from the teachings of the examples.

[0031] For ease of description, spatial relationship terms such as "above", "upper", "below", and "lower" may be used herein to describe the relationship of one element to another as shown in the figures. Such spatial relationship terms are intended to include different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is flipped, an element described as being "above" or "upper" relative to another element will subsequently be "below" or "lower" relative to the other element. Thus, the term "above" includes both the orientations of "above" and "below" depending on the spatial orientation of the device. The device can also be positioned in other ways (e.g., rotated 90 degrees or in other orientations), and the spatial relationship terms used herein will be interpreted accordingly.

[0032] The terms used herein are for the purpose of describing various examples only and are not intended to limit the present disclosure. Unless the context clearly indicates otherwise, the singular forms are also intended to include the plural forms. The terms "comprising", "including" and "having" enumerate the stated features, quantities, operations, components, elements and / or combinations thereof that exist, but do not preclude the existence or addition of one or more other features, quantities, operations, components, elements and / or combinations thereof.

[0033] Due to manufacturing techniques and / or tolerances, variations in the shapes shown in the drawings may occur. Accordingly, the examples described herein are not limited to the specific shapes shown in the drawings, but include changes in shape that occur during manufacturing.

[0034] The features of the examples described herein can be combined in various ways that will be apparent after understanding the disclosure of the present application. Moreover, although the examples described herein have various configurations, other configurations are possible, as will be apparent after understanding the disclosure of the present application.

[0035] According to a first aspect of the present invention, a battery cap is provided, which includes a top cover 10 and a pressure relief member 20.

[0036] Hereinafter, the specific structure of the battery cap according to the present embodiment will be described as above.

[0037] As Figure 1 and Figure 2 shown, the top cover 10 is formed into a plate-like structure. In the present embodiment, the battery is a cylindrical battery, and the top cover 10 is formed into a circular plate-like structure; the pressure relief member 20 is formed into a plate-like structure or a sheet-like structure, and has a recessed notch on the surface. When the battery is in a thermal runaway situation, the internal pressure of the battery increases, causing the notch on the pressure relief member 20 to crack, so that the inside and outside of the battery are communicated, thereby realizing exhaust pressure relief and alleviating thermal runaway. The pressure relief member 20 can be an explosion-proof valve or an explosion-proof sheet.

[0038] In the present embodiment, as Figure 2 and Figure 3 shown, the pressure relief member 20 is disposed on the side of the top cover 10 facing the inside of the battery. A covering portion 21 extending toward the top cover 10 is formed on the circumferential edge of the pressure relief member 20. The covering portion 21 is formed into an annular structure. The covering portion 21 surrounds the circumferential edge of the top cover 10. The covering portion 21 and a partial edge of the top cover 10 are welded together to form a welding portion 30. In this way, the welding portion 30 is disposed between the top cover 10 and the pressure relief member 20, and to a certain extent, the influence of the welding portion 30 on the internal resistance is reduced. Preferably, the covering portion 21 is formed into a closed annular structure, and the welding portion 30 is formed by welding the inner circumferential wall of the covering portion 21 and a partial circumferential edge of the top cover 10.

[0039] The welded part 30 can be understood as a weld seam formed through a welding process. Preferably, the laser weld seam has a penetration depth and a weld width. In this embodiment, from the perspective of Figure 2 and Figure 3 , the welded part 30 is formed by a laser path from the side of the battery cap facing the outside of the battery downward. The part of the welded part 30 that does not axially extend beyond the part of the covering part 21 facing the outside of the battery forms an effective molten pool. The part of the welded part 30 that forms the effective molten pool can achieve the reliable assembly of the pressure relief part 20 and the top cover 10. The effective penetration depth of the welded part 30 is h, and the effective weld width of the welded part 30 is w, where 0.45 mm ≤ w ≤ 1.5 mm; in the axial direction of the battery cap, the height dimension of the covering part 21 is H, and 0.8 ≤ h / H ≤ 1.2. In this way, while ensuring reliable welding strength, it is also possible to avoid the parameters of the effective weld width or h / H being too large and affecting the internal resistance electrical performance, thereby ensuring the output power and performance of the battery, reducing the risk of battery thermal runaway, and improving the safety performance and service life of the battery.

[0040] Furthermore, in this embodiment, as shown in Figure 3 , 0.3 mm ≤ H ≤ 1.15 mm. In this way, problems such as welding through or affecting the welding strength due to too small an H size are avoided, and the situation where the size of the battery cap is too thick axially due to too large an H size, resulting in a reduction in the energy density of the battery, is also avoided.

[0041] In this embodiment, as shown in Figure 3 , the surface of the top cover 10 facing the outside of the battery protrudes from the end of the covering part 21 facing the outside of the battery, so that in the axial direction of the battery cap, a height difference L is formed between the top cover 10 and the covering part 21, where 0.05 mm ≤ L ≤ 0.2 mm. In this way, while not affecting the strength of the welded part 30, better sealing cooperation with the seal 40 described below can be achieved.

[0042] Furthermore, in this embodiment, as shown in Figure 3 , in the axial direction of the battery cap, the thickness dimension of the top cover 10 is K, where 0.5 mm ≤ K ≤ 1.2 mm. In this way, it is ensured that the top cover 10 has sufficient structural strength, the welded part 30 is reliably formed, deformation of the top cover 10 caused by the welding process is avoided, and the situation where the overall thickness dimension of the battery cap is increased due to too large a K size and the welding difficulty is also increased is avoided.

[0043] It should be noted that before the pressure relief part 20 is welded to the top cover 10, there is a gap between the covering part 21 and the top cover 10 in the radial direction of the battery cap, and the gap range is 0 to 0.1 mm. In this way, the smooth assembly of the pressure relief part 20 and the top cover 10 is ensured, the welding requirements are met, and the welding effect is not affected.

[0044] In this embodiment, as shown in Figure 1 ​​​​​​​​​​​As shown, a plurality of welding portions 30 are provided. The plurality of welding portions 30 are evenly distributed around the top cover 10 at equal intervals. The number of welding portions 30 can be two, three, four,... In this way, the stress generated after welding is reduced, making the overall structure of the battery cap more evenly stressed after welding.

[0045] In this embodiment, as Figure 1 shown, the welding portion 30 is formed into an arc structure, and the center of the arc structure of the welding portion 30 is set on the axis of the battery cap. In this way, the bending arc of the welding portion 30 better covers the gap between the covering portion 21 and the top cover 10, ensuring the connection strength between the top cover 10 and the pressure relief member 20.

[0046] In addition, in this embodiment, as Figure 1 shown, the total length dimension of the welding portion 30 (i.e., the total arc length dimension of the arc-shaped welding portion 30) is S1. That is, when a plurality of welding portions 30 are provided, S1 is the sum of the arc lengths of all the welding portions 30, and the length of the circumferential edge of the top cover 10 is S0. That is, S0 is the outer circumference of the top cover 10, and 0.30 ≤ S1 / S0 ≤ 0.65. In this way, it is avoided that the ratio of S1 / S0 is too large and affects the internal resistance, and it is also avoided that the ratio is too small and affects the welding strength.

[0047] Next, the welding strength P and the internal resistance M after welding of the battery caps with different dimensions of w, h, H, S1, and S0 are detected. When the welding strength P between the top cover 10 and the pressure relief member 20 ≥ 0.9 Mpa and the internal resistance M after welding ≤ 0.5 mΩ, the detection is qualified. The detection results are shown in Tables 1 and 2 below.

[0048] Table 1

[0049] w / mm h / mm H / mm h / H S1 / mm S0 / mm S1 / S0 P / Mpa M / mΩ Example 1 0.47 0.26 0.30 0.867 11.4 37.68 0.303 0.94 0.32 Example 2 0.53 0.31 0.30 1.033 18.3 37.68 0.486 1.21 0.21 Example 3 0.45 0.35 0.30 1.167 24.4 37.68 0.648 0.92 0.33 Example 4 0.69 0.48 0.60 0.800 18.7 56.52 0.331 1.21 0.42 Example 5 1.32 0.59 0.60 0.983 26.8 56.52 0.474 1.32 0.46 Example 6 0.95 0.72 0.60 1.200 36.4 56.52 0.644 0.97 0.37 Example 7 0.91 0.69 0.85 0.812 24.1 78.5 0.307 1.27 0.18 Example 8 1.21 0.77 0.85 0.906 36.9 78.5 0.470 0.90 0.17 Example 9 1.50 0.99 0.85 1.165 49.7 78.5 0.633 1.35 0.22 Example 10 1.45 0.94 1.15 0.817 30.1 94.2 0.320 1.23 0.48 Example 11 1.39 1.04 1.15 0.904 55.9 94.2 0.593 1.41 0.23 Example 12 1.48 1.37 1.15 1.191 61.2 94.2 0.650 1.46 0.43

[0050] Table 2

[0051]

[0052]

[0053] Referring to Table 1 above, it can be seen that in Examples 1 to 12, the limiting conditions of 0.45 mm ≤ w ≤ 1.5 mm and 0.8 ≤ h / H ≤ 1.2 are all satisfied, and the internal resistance after welding is less than 0.5 mΩ, meeting the requirements. In addition, in Examples 1 to 12, the limiting condition of 0.30 ≤ S1 / S0 ≤ 0.65 is also satisfied, which can ensure the welding strength between the pressure relief member 20 and the top cover 10 and will not increase the internal resistance.

[0054] Referring to Table 2, it can be seen that in Comparative Examples 1 to 4, the welding strength P decreases due to the too small size of w; in Comparative Examples 5 to 8, the internal resistance M after welding increases due to the too small size of w; in Comparative Examples 9 to 12, the welding strength P decreases due to the too small parameter of h / H; in Comparative Examples 13 to 16, the internal resistance M after welding increases due to the too large parameter of h / H; in Comparative Examples 17 to 20, the welding strength P decreases due to the too small parameter of S1 / S0; in Comparative Examples 21 to 24, the internal resistance M after welding increases due to the too large parameter of S1 / S0.

[0055] In addition, in this embodiment, as Figure 2 shown, the battery cap further includes a seal 40; the seal 40 has elasticity and insulation properties, for example, a sealing ring made of rubber material can be used; the seal 40 is disposed around the circumferential edge of the pressure relief member 20, and when the battery cap is assembled with the battery case, the battery case can squeeze the sealing ring to achieve a sealed assembly.

[0056] Specifically, in this embodiment, as Figure 2 and Figure 3 shown, one end of the seal 40 facing the outside of the battery is formed as a flanging portion 41 protruding from the top cover 10. After the battery cap is assembled to the battery case, the opening of the battery case is folded inward, so that the flanging portion 41 is bent and crimped with the top cover 10 to cover the welding portion 30, thereby achieving the sealed assembly of the battery cap and the battery case.

[0057] In a preferred embodiment, as Figure 2 and Figure 3 shown, the flanging portion 41 is formed as an annular structure to ensure the sealed assembly effect. A convex portion 401 is formed on the inner circumferential wall of the flanging portion 41, and the convex portion is preferably formed as an annular structure. The convex portion 401 can be formed as a rotating body with a triangular cross section; when the flanging portion 41 is bent, the convex portion 401 is squeezed and deformed to press against one end of the covering portion 21 facing the outside of the battery and at least part of the welding portion 30, so as to improve the assembly sealing performance between the pressure relief member 20 and the top cover 10.

[0058] According to a battery cap provided by the present invention, a covering portion extending toward the top cover is formed at the circumferential edge of the pressure relief member. The covering portion surrounds the circumferential edge of the top cover, and a welding portion is formed by welding the covering portion and a partial edge of the top cover. In this way, the welding portion is arranged between the top cover and the pressure relief member, which reduces the influence of the welding portion on the internal resistance to a certain extent. The effective penetration depth of the welding portion is h, and the effective weld width of the welding portion is w, where 0.45 mm ≤ w ≤ 1.5 mm. In the axial direction of the battery cap, the height dimension of the covering portion is H, and 0.8 ≤ h / H ≤ 1.2. In this way, while ensuring reliable welding strength, it is also possible to avoid the parameters of the effective weld width or h / H being too large and affecting the internal resistance electrical performance.

[0059] According to a battery provided by the present invention, it includes the battery cap as described above. After the pressure relief member and the top cover are welded, the internal resistance is within the standard range and has reliable welding strength, thereby ensuring the output power and performance of the battery, reducing the risk of battery thermal runaway, and improving the safety performance and service life of the battery.

[0060] Finally, it should be noted that the above-described embodiments are only specific embodiments of the present application, used to illustrate the technical solutions of the present application, rather than limiting them. The protection scope of the present application is not limited thereto. Although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that any person skilled in the art within the technical scope disclosed by the present application can still modify the technical solutions recorded in the foregoing embodiments, or can easily think of changes, or make equivalent replacements for some of the technical features; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A battery cap, characterized in that, Comprising: Top cover; Pressure relief member, disposed on a side of the top cover facing the interior of the battery. A circumferential edge of the pressure relief member forms a covering portion extending towards the top cover. The covering portion surrounds the circumferential edge of the top cover. The covering portion and a partial edge of the top cover are welded together to form a welded portion. The effective penetration depth of the welded portion is h, and the effective weld width of the welded portion is w, where 0.45 mm ≤ w ≤ 1.5 mm; In the axial direction of the battery cap, the height dimension of the covering portion is H, and 0.8 ≤ h / H ≤ 1.

2.

2. The battery cap according to claim 1, wherein, 0.3 mm ≤ H ≤ 1.15 mm.

3. The battery cap according to claim 1, characterized in that, A surface of the top cover facing the exterior of the battery protrudes from an end of the covering portion facing the exterior of the battery, such that in the axial direction of the battery cap, a height difference L is formed between the top cover and the covering portion, where 0.05 mm ≤ L ≤ 0.2 mm.

4. The battery cap according to claim 3, characterized in that, In the axial direction of the battery cap, the thickness dimension of the top cover is K, where 0.5 mm ≤ K ≤ 1.2 mm.

5. The battery cap according to claim 1, characterized in that, The welded portion is formed into an arc-shaped structure. The total arc length dimension of the welded portion is S1, and the length of the circumferential edge of the top cover is S0, where 0.30 ≤ S1 / S0 ≤ 0.

65.

6. The battery cap according to claim 1, characterized in that, A plurality of the welded portions are provided, and the plurality of welded portions are evenly distributed around the top cover at intervals.

7. The battery cap according to claim 1, wherein, The welded portion is formed into an arc-shaped structure, and the center of the welded portion is disposed on the axis of the battery cap.

8. The battery cap according to claim 1, characterized in that, Further comprising: Sealing member, surrounding the circumferential edge of the pressure relief member. An end of the sealing member facing the exterior of the battery is formed into a flanging portion protruding from the top cover. The flanging portion is bent to be press-fitted with the top cover to cover the welded portion.

9. The battery cap according to claim 8, characterized in that, The flanging portion is formed into an annular structure. A convex portion is formed on an inner circumferential wall of the flanging portion. The flanging portion is bent such that the convex portion is press-fitted with the covering portion and at least a part of the welded portion.

10. A battery, characterized in that, Comprising the battery cap according to any one of claims 1 to 9.

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