Battery cell cover plate and battery cell

Abstract

The present application relates to the technical field of batteries, and in particular to a battery cell cover plate and a battery cell. The battery cell cover plate comprises: a cover plate body provided with a mounting hole, an inwardly protruding boss portion being formed on an inner wall of the mounting hole, and the size of the boss portion in a first direction being c; and a pressure relief member provided on one side of the boss portion in the first direction, and welded to the boss portion, so as to form a welding portion between the pressure relief member and the boss portion, wherein the size of the welding portion on the boss portion along the first direction is h, and 0.2 mm≤h≤(c-0.3) mm; the size of the welding portion on the boss portion along a second direction is w, and w≥0.2 mm; and the size of the welding portion on the pressure relief member along the second direction is W1, and W1≥w. The present application ensures reliable welding between the cover plate body and the pressure relief member, enhances the connection strength between the cover plate body and the pressure relief member, prevents the battery cell from electrolyte leakage caused by cracking and damage of the welding portion, and can also avoid appearance degradation due to deformation of the cover plate body caused by burn-through.

Description

Battery cell cover plate and battery cell

[0001] Cross-reference to related applications

[0002] The present application claims priority to the Chinese patent application No. CN202411260510.2, filed on September 10, 2024, entitled "Battery cell cover plate and battery cell", the entire content of which is incorporated herein by reference. TECHNICAL FIELD

[0003] The present application relates to the technical field of battery, in particular to a battery cell cover plate and a battery cell. BACKGROUND

[0004] A lithium-ion power battery generally includes a battery internal structure and a battery external structure. The battery internal structure mainly includes a battery cell pole group, and the battery external structure mainly includes a battery cell cover plate and a battery cell shell. The battery cell shell provides a containing space for the battery cell pole group, and the battery cell cover plate and the battery cell shell are connected by welding to form a closed space, thereby forming a complete lithium-ion battery structure. An explosion-proof valve is installed on the cover plate of the battery cell to prevent the explosion-proof valve from being broken under a certain pressure when the internal chemical reaction of the battery cell intensifies to produce gas, thereby releasing energy and relieving the battery cell from out of control.

[0005] The explosion-proof valve and the cover plate are connected by tailor welding. The welding connection between the explosion-proof valve and the cover plate is unreliable, and the welding yield is low. Cracking and damage, poor sealing of the explosion-proof valve and the cover plate, and the like may occur at the welding position. In particular, when gas is generated during the charging and discharging process of the battery, the internal gas pressure of the battery may form a shearing force at the welding position, the welding seam is prone to cracking, resulting in poor sealing of the battery, causing the battery to leak, and even causing a safety accident in severe cases. In addition, the welding may affect the appearance of the cover plate, increase the production cost, and reduce the production efficiency.

[0006] SUMMARY

[0007] Therefore, the present application aims to provide a battery cell cover plate and a battery cell to solve the problems of cracking and damage, poor sealing, and leakage caused by unreliable welding between the existing explosion-proof valve and the cover plate, or the problems of affecting the appearance of the cover plate, increasing the production cost, and reducing the production efficiency caused by welding.

[0008] The first object of the present application is to provide a battery cell cover plate, comprising:

[0009] A cover plate body is provided with a mounting hole. An inner wall of the mounting hole is formed with a boss portion protruding inward along a radial direction of the mounting hole, so that the mounting hole is formed as a stepped hole. The size of the boss portion in the first direction is c.

[0010] A pressure relief member is arranged on one side of the boss portion in the first direction and is welded to the boss portion to form a weld between the pressure relief member and the boss portion;

[0011] In the first direction, the size of the weld on the boss portion is h, and 0.2mm≤h≤(c-0.3)mm; in the second direction, the size of the weld on the boss portion is w, and w≥0.2mm; in the second direction, the size of the weld on the pressure relief member is W1, and W1≥w.

[0012] Beneficial effects: The pressure relief member is welded to the mounting hole of the cover plate body, and a weld is formed between the cover plate body and the pressure relief member. By limiting the size h of the weld in the first direction and the size w in the second direction, respectively satisfying 0.2mm≤h≤(c-0.3)mm and w≥0.2mm, the welding of the cover plate body and the pressure relief member is reliable, the connection strength of the cover plate body and the pressure relief member is improved, the cracking and damage of the weld are avoided to cause the battery leakage, the use safety of the battery is ensured, the use requirements of the battery are met, or the welding through is avoided to cause the deformation of the cover plate body to affect the appearance, thereby reducing the production cost and improving the production efficiency.

[0013] In an optional embodiment, the maximum thickness of the pressure relief member in the first direction is e, and e≥0.2mm.

[0014] In an optional embodiment, the pressure relief member is arranged on the side of the boss portion facing the inside of the battery.

[0015] In an optional embodiment, the pressure relief member is formed with a recessed notch portion to reduce the size of part of the pressure relief member in the first direction.

[0016] In an optional embodiment, the weld is formed in an annular structure, and the distance between the notch portion and the inner ring wall of the weld in the second direction is a, and (W1+1.5)mm≤a≤10mm.

[0017] In an optional embodiment, the notch portion is arranged on the side of the pressure relief member facing the outside of the battery.

[0018] In an optional embodiment, in the second direction, the side wall of the pressure relief member has a gap g with the hole wall of the mounting hole, and 0.05mm≤g≤1mm.

[0019] In an optional embodiment, the thickness of the cover plate body in the first direction is f, and 1.5mm≤f≤5mm.

[0020] In an alternative embodiment, the distance between the sidewall of the boss portion and the sidewall of the pressure relief member in the second direction is b, and W1≤b≤15mm.

[0021] A second object of the present application is to provide an electric core comprising the electric core cover plate according to any one of the technical solutions. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the specific embodiments or the prior art, the drawings needed to be used in the specific embodiments or the prior art description will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort.

[0023] Fig. 1 is an exploded view of the structure of the cover plate main body and the pressure relief member in the electric core cover plate provided by the embodiments of the present application;

[0024] Fig. 2 is a structural schematic view of the cover plate main body and the pressure relief member in the electric core cover plate provided by the embodiments of the present application before welding;

[0025] Fig. 3 is a sectional view along A-A in Fig. 2;

[0026] Fig. 4 is an enlarged structural schematic view of B in Fig. 3;

[0027] Fig. 5 is a structural schematic view of the welding of the cover plate main body and the pressure relief member in the electric core cover plate provided by the embodiments of the present application.

[0028] Legend of reference signs: 10-cover plate main body; 11-mounting hole; 101-boss portion; 111-first step portion; 112-second step portion; 20-pressure relief member; 21-score portion; 30-welding portion; 40-pole; 50-insulating member; D1-first direction; D2-second direction. DETAILED DESCRIPTION

[0029] In order to make the objects, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without any creative effort are within the scope of protection of the present application.

[0030] According to the first aspect of the present application, an electric core cover plate is provided, which specifically comprises a cover plate main body 10 and a pressure relief member 20.

[0031] In the following, the specific structure of the electric core cover plate according to the present embodiments will be described.

[0032] In the embodiment, as shown in FIGS. 1-4, the cover plate body 10 is formed in a sheet structure, such as a rectangular or circular sheet structure, and the mounting hole 11 is formed in the cover plate body 10 as a through hole structure penetrating the cover plate body 10. The thickness dimension of the cover plate body 10 in the first direction D1 is f, and the first direction D1 is the thickness direction of the cover plate body 10.

[0033] In the preferred embodiment, as shown in FIG. 4, 1.5 mm≤f≤5 mm, so as to avoid that f is too small to cause the cover plate body 10 to be deformed obviously when the battery cell is stressed due to insufficient strength of the cover plate body 10, resulting in failure of the battery cell, and avoid that f is too large to waste materials, increase the cost and the weight of the battery cell.

[0034] Further, in the embodiment, as shown in FIGS. 1-5, the inner wall of the mounting hole 11 is formed with a boss portion 101 protruding inwardly along the radial direction of the mounting hole 11, so that the mounting hole 11 is formed as a stepped hole. The boss portion 101 is preferably formed in an annular structure. Specifically, the hole wall of the mounting hole 11 includes a first step portion 111 and a second step portion 112 arranged along the first direction D1, and the second step portion 112 is the inner wall of the boss portion 101. The size of the through hole surrounded by the first step portion 111 in the second direction D2 is greater than the size of the through hole surrounded by the second step portion 112 in the second direction D2, i.e., the hole diameter of the through hole surrounded by the first step portion 111 is greater than the hole diameter of the through hole surrounded by the second step portion 112.

[0035] The pressure relief member 20 is arranged on one side of the boss portion 101 in the first direction D1, and the boss portion 101 can support and limit the pressure relief member 20. The size of the boss portion 101 in the first direction D1 is c.

[0036] As shown in FIG. 5, specifically, the pressure relief member 20 is welded with the boss portion 101 to form a welding portion 30 between the pressure relief member 20 and the boss portion 101, the welding portion 30 can be understood as a welding mark formed under a welding process, that is, part of the welding portion 30 is arranged on the pressure relief member 20, and the remaining part of the welding portion 30 is arranged on the boss portion 101, the welding portion 30 is formed as a closed annular structure to ensure that there is no gap between the pressure relief member 20 and the cover plate body 10, the size of the welding portion 30 in the first direction D1 is h, 0.2mm≤h≤(c-0.3)mm; along the second direction D2, the size of the welding portion 30 on the boss portion 101 is w, w≥0.2mm; along the second direction D2, the size of the welding portion 30 on the pressure relief member 20 is W1, W1≥w, wherein h can be understood as the penetration of the welding mark formed by the welding process, w and W1 can be understood as the width of the welding mark formed by the welding process, under the limitation conditions of 0.2mm≤h≤(c-0.3)mm and w≥0.2mm, the welding between the cover plate body 10 and the pressure relief member 20 can be reliable, the connection strength between the cover plate body 10 and the pressure relief member 20 is improved, and the situation that the welding portion 30 is cracked and damaged due to the too small size of h to cause the battery cell to leak is avoided, in addition, the situation that the cover plate body 10 is welded through due to the too large size of h to cause the cover plate body 10 to lose the limiting effect on the pressure relief member 20 and affect the appearance is also avoided, thereby realizing the reduction of production cost and the improvement of production efficiency.

[0037] It should be noted that in the present embodiment, the welding is performed on the side of the pressure relief member 20 away from the boss portion 101, so that the pressure relief member 20 is hot melt welded with the boss portion 101.

[0038] In the preferred embodiment, the welding portion 30 does not contact the first step portion 111.

[0039] In the present embodiment, the first direction D1 is perpendicular to the second direction D2, when the cover plate body 10 is formed as a rectangular sheet structure, the second direction D2 can be the length direction of the cover plate body 10.

[0040] In the present embodiment, the pressure relief member 20 is formed with a recessed score portion 21 to reduce the size of part of the pressure relief member 20 in the first direction D1, that is, to reduce the thickness of the position of the score portion 21 on the pressure relief member 20, so that when a large amount of gas is generated inside the battery cell due to the failure of the battery cell, the gas pressure in the battery cell can break the score portion 21, so that the pressure relief member 20 cracks along the score portion 21, thereby balancing the pressure inside and outside the battery cell to ensure the safe use of the battery cell. In the present embodiment, the score portion 21 can be formed as a closed annular structure or an open annular structure, or can be a plurality of linear structures arranged in cross, as long as at least part of the score portion 21 can be timely broken and cracked under the opening pressure of the pressure relief member 20, so that the inside and outside of the battery cell are communicated to achieve pressure relief.

[0041] In the preferred embodiment, as shown in FIG. 5, in the second direction D2, the distance between the score portion 21 and the ring wall inside the welding portion 30 is a, (W1+1.5)mm≤a≤10mm, so as to avoid that the distance between the score portion 21 and the welding portion 30 is too small, which is easily affected by the thermodynamics of the welding process, causing the score portion 21 to crack or open prematurely before the pressure relief requirement is reached, and to avoid that the size of a is too large, which affects the opening area of the pressure relief member 20 and reduces the pressure relief efficiency, and wastes materials.

[0042] In the preferred embodiment, as shown in FIG. 4, the maximum thickness dimension of the pressure relief member 20 in the first direction D1 is e, e≥0.2mm, so as to avoid that the welding portion 30 is welded through.

[0043] In the preferred embodiment, as shown in FIG. 4, in the second direction D2, the distance between the side wall of the boss portion 101 and the side wall of the pressure relief member 20 is b, i.e. the distance between the hole wall of the through hole surrounded by the second step portion 112 in the second direction D2 as described above and the side wall of the pressure relief member 20 is b, W1≤b≤15mm, so as to ensure that the boss portion 101 can play a good limiting and supporting role on the pressure relief member 20, avoid that the size of b is too small, and the size W1 of the welding portion 30 on the pressure relief member 20 in the second direction D2 has sufficient width, and also avoid that the welding portion 30 affects the score portion 21, so as to ensure that the pressure relief member 20 can be smoothly opened under the rated pressure.

[0044] In the present embodiment, as shown in FIG. 3, the pressure relief member 20 is arranged on the side of the boss portion 101 facing the inside of the battery cell, so that the pressure relief member 20 is arranged on the side of the cover plate body 10 facing the inside of the battery cell, so as to avoid that the structure outside the battery cell extrudes or even damages the pressure relief member 20.

[0045] Further, in the present embodiment, as shown in FIG. 4 and FIG. 5, the score portion 21 is arranged on the side of the pressure relief member 20 facing the outside of the battery cell, so that under the rated pressure, the score portion 21 is easy to crack, and the pressure relief member 20 can be smoothly opened.

[0046] In the preferred embodiment, as shown in FIG. 4, in the second direction D2, the pressure relief member 20 has a gap g between the side wall and the hole wall of the mounting hole 11, i.e. the distance between the first step portion 111 and the pressure relief member 20 is g, 0.05mm≤g≤1mm, so as to avoid that the gap g is too small, causing the pressure relief member 20 to be difficult to be installed into the mounting hole 11, and to avoid that the gap g is too large, affecting the welding yield of the pressure relief member 20 and the cover plate body 10.

[0047] h, e, w, W1, a, c, b and f are measured after the cover plate body 10 and the pressure relief member 20 are assembled, and the assembled battery cell cover plate is subjected to a helium leak detection test, and in this embodiment, the helium leak detection rate is higher than 1x10 -7 pa·m 3 / s is detected to be qualified, and the specific test parameters are shown in the following table: Note: "NG" in the table means that the helium leak detection test is unqualified, and "OK" means that the helium leak detection test is qualified.

[0048] As can be seen from the above table, in Example 1, h = 0.19 mm, which is not within the size requirement of 0.2 mm≤h≤(c-0.3) mm, and after the cover plate body 10 and the pressure relief member 20 are welded, the helium leak rate does not meet the requirements; in Example 3, e = 0.18 mm, which is not within the limited range of e≥0.2 mm, and after the cover plate body 10 and the pressure relief member 20 are welded, the helium leak rate does not meet the requirements; in Example 4, w = 0.19 mm, which is not within the limited range of w≥0.2 mm, and after the cover plate body 10 and the pressure relief member 20 are welded, the helium leak rate does not meet the requirements; in Example 7, a = 1.83 mm, which is not within the limited range of (W1+1.5) mm≤a≤10 mm, and after the cover plate body 10 and the pressure relief member 20 are welded, the helium leak rate does not meet the requirements; in Example 8, h = 0.71 and c = 1 mm, so h is not within the limited range of 0.2 mm≤h≤(c-0.3) mm, and after the cover plate body 10 and the pressure relief member 20 are welded, the helium leak rate does not meet the requirements; and in Example 2, Example 5, Example 6, Example 9, Example 10, Example 11 and Example 12, h, e, w, W1, a, c, b and f are all within the limited range as described above, and after the cover plate body 10 and the pressure relief member 20 are welded, the helium leak rate meets the requirements.

[0049] In addition, in this embodiment, as shown in FIGS. 1 and 2, the battery cell cover plate further includes a pole 40 and an insulating member 50, the pole 40 is installed on the cover plate body 10 and connected with the tab on the pole group inside the battery cell, and the number of the pole 40 on the cover plate body 10 can be one or more; the insulating member 50 is arranged on the cover plate body 10, and is used to separate the cover plate body 10 from the inside of the battery cell or to separate the cover plate body 10 and the pole 40, so as to play an insulating role, and the insulating member 50 can be a plastic member.

[0050] According to the cell cover plate provided in the application, the pressure relief member is welded on the mounting hole of the cover plate body, and a welding portion is formed between the cover plate body and the pressure relief member. By limiting the size h in the first direction and the size w in the second direction of the welding portion, 0.2mm≤h≤(c-0.3)mm and w≥0.2mm are respectively satisfied, so as to ensure reliable welding of the cover plate body and the pressure relief member, improve the connection strength of the cover plate body and the pressure relief member, avoid the case that the welding portion is cracked and damaged to cause the cell to leak, or avoid the problem that welding is penetrated to cause the cover plate body to be deformed to affect the appearance.

[0051] According to the cell provided in the application, the welding portion has sufficient strength, so as to ensure the connection strength of the cover plate body and the pressure relief member, thereby improving the safety of the cell in use, and the case that welding is penetrated can also be avoided, so as to reduce the production cost of the cell and improve the production efficiency of the cell.

[0052] Although the embodiments of the application are described in combination with the drawings, various modifications and variations can be made by those skilled in the art without departing from the spirit and scope of the application, and such modifications and variations all fall within the scope defined by the appended claims. Industrial applicability

[0053] The cell cover plate provided in the application, the pressure relief member is welded on the mounting hole of the cover plate body, and a welding portion is formed between the cover plate body and the pressure relief member. By limiting the size h in the first direction and the size w in the second direction of the welding portion, 0.2mm≤h≤(c-0.3)mm and w≥0.2mm are respectively satisfied, so as to ensure reliable welding of the cover plate body and the pressure relief member, improve the connection strength of the cover plate body and the pressure relief member, avoid the case that the welding portion is cracked and damaged to cause the cell to leak, ensure the safety of the cell in use, meet the use requirements of the cell, or avoid the problem that welding is penetrated to cause the cover plate body to be deformed to affect the appearance, thereby reducing the production cost and improving the production efficiency.

Claims

1. An electrode cover plate, characterized by, The battery cell cover plate comprises: a cover plate body provided with a mounting hole, an inner wall of the mounting hole being formed with a boss portion protruding inward along a radial direction of the mounting hole, so that the mounting hole is formed as a stepped hole, a dimension of the boss portion in a first direction being c; a pressure relief member arranged on one side of the boss portion in the first direction and welded to the boss portion to form a welding portion between the pressure relief member and the boss portion; in the first direction, a dimension of the welding portion on the boss portion being h, 0.2mm≤h≤(c-0.3)mm; in a second direction, a dimension of the welding portion on the boss portion being w, w≥0.2mm; in the second direction, a dimension of the welding portion on the pressure relief member being W1, W1≥w.

2. The cell cover plate of claim 1, wherein, a maximum thickness dimension of the pressure relief member in the first direction being e, e≥0.2mm.

3. The cell cover plate of claim 2, wherein, the pressure relief member is arranged on a side of the boss portion facing an inside of a battery cell.

4. The cell cover plate of claim 1, wherein, the pressure relief member is formed with a recessed score portion to reduce a dimension of a part of the pressure relief member in the first direction.

5. The cell cover plate of claim 4, wherein, the welding portion is formed as an annular structure, a distance between the score portion and a ring wall inside the welding portion in the second direction being a, (W1+1.5)mm≤a≤10mm.

6. The cell cover plate of claim 4, wherein, the score portion is arranged on a side of the pressure relief member facing an outside of a battery cell.

7. The cell cover plate of claim 1, wherein, in the second direction, a gap between a side wall of the pressure relief member and a hole wall of the mounting hole being g, 0.05mm≤g≤1mm.

8. The cell cover plate of claim 1, wherein, a thickness dimension of the cover plate body in the first direction being f, 1.5mm≤f≤5mm.

9. The cell cover plate of claim 1, wherein, a distance between a side wall of the boss portion and a side wall of the pressure relief member in the second direction being b, W1≤b≤15mm.

10. An electric cell characterized by a battery cell cover plate comprising any one of claims 1 to 9.

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