Battery sealing structure and battery

Abstract

A battery sealing structure and a battery. The battery sealing structure comprises: a battery cell cover plate or a casing, provided with a liquid injection hole running through a main body thereof; and a sealing member, welded and connected to the liquid injection hole, so that a welding portion is formed between at least a portion of the circumferential side wall of the sealing member and at least a portion of the hole wall of the liquid injection hole, wherein the welding portion has a penetration depth L1=500-1000 μm and a weld width L2≥500 μm. The battery sealing structure ensures a reliable connection between the sealing member and the liquid injection hole by defining the sizes of the penetration depth L1 and the weld width L2 of the welding portion, thereby effectively preventing electrolyte leakage, meeting sealing requirements of battery electrolytes, improving the yield of batteries and prolonging the service life of the batteries, and ensuring usage safety of the batteries.

Description

Battery sealing structure and battery

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese patent application number CN202410129799.8, entitled “Battery Sealing Structure and Battery,” filed with the Patent Office of China on January 31, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present application relates to the field of battery technology, and in particular to a battery sealing structure and a battery. Background Art

[0004] The battery top cover is a key component of a power battery. It is assembled with the housing to form a closed structure for accommodating battery cells. The battery top cover features an injection hole for injecting electrolyte into the housing. After injection, the hole needs to be sealed to isolate the battery cells from the outside environment and ensure they are enclosed in the chemical environment required for their operation. To prevent leakage of electrolyte from the housing, the injection hole needs to be sealed. Currently, laser sealing is used to connect the sealing structure to the battery top cover. However, the welding effect between the sealing structure and the battery top cover is unsatisfactory, resulting in poor sealing of the sealing structure and the risk of electrolyte leakage, which reduces battery life and safety.

[0005] Application Contents

[0006] In view of this, the purpose of this application is to provide a battery sealing structure and a battery to solve the problem that the welding effect of the existing sealing structure of the injection hole is not ideal, resulting in poor sealing effect of the sealing structure and the risk of electrolyte leakage, thereby reducing the battery life and safety of use.

[0007] In a first aspect, the present application provides a battery sealing structure, wherein the battery sealing structure comprises:

[0008] The cell cover or housing is formed with a liquid injection hole penetrating through the body thereof;

[0009] The sealing member is welded to the injection hole so that a welding portion is formed between at least part of the circumferential side wall of the sealing member and at least part of the hole wall of the injection hole, the penetration depth L1 of the welding portion is 500 to 1000 μm, and the penetration width L2 of the welding portion is ≥500 μm.

[0010] Beneficial effect: The battery sealing structure of the present application welds the seal to the injection hole to form a welding part at the connection. By limiting the size of the weld depth L1 and the weld width L2 of the welding part, it ensures that the seal is reliably connected to the injection hole, effectively preventing electrolyte leakage, thereby meeting the sealing requirements of the battery electrolyte, thereby improving the battery's yield and service life, and ensuring the safety of battery use.

[0011] In an optional embodiment, the elastic strain portion extends in a broken line shape along a direction from the notch to the base.

[0012] In an optional embodiment, the compressive strength of the weld is greater than 1.2 MPa.

[0013] In an optional embodiment, the leakage rate of the welding portion is less than 1×10 -6 pa·m 3 / s.

[0014] In an optional embodiment, the welding power for forming the weld portion is 6000-8000W.

[0015] In an optional embodiment, the energy for forming the weld portion is 10-40J.

[0016] In an optional embodiment, the welding speed for forming the weld portion is 7 to 10 mm / s.

[0017] In an optional embodiment, the welding portion is formed by sequentially connecting a plurality of welding spots; the overlapping rate of two adjacent welding spots is not less than 50%, wherein the overlapping rate = (L2-L3) / L2.

[0018] In an optional embodiment, the sealing member provided with the liquid injection hole is made of the same material as the battery cell cover or shell.

[0019] In an optional embodiment, the injection hole is formed as a countersunk hole, so that the side wall of the injection hole is formed into a boss structure, and the two ends of the injection hole in the axial direction are respectively formed as a first mounting portion and a second mounting portion, the radial dimension of the first mounting portion is larger than the radial dimension of the second mounting portion, and the sealing member is provided on the first mounting portion;

[0020] The ratio of the penetration depth L1 to the groove depth L4 of the first mounting portion is K1 = L1 / L4 > 0.5;

[0021] And / or, a ratio of the weld width L2 to the groove depth L4 of the first mounting portion K2 = L2 / L4 > 0.5.

[0022] In an optional embodiment, the battery sealing structure further includes:

[0023] The elastic member is arranged on the second mounting portion.

[0024] In a second aspect, the present application further provides a battery, comprising the battery sealing structure described in any of the above technical solutions;

[0025] The battery is a square battery, and the length of the square battery is 100-600 mm, the width is 50-250 mm, and the height is 10-100 mm;

[0026] Alternatively, the battery is a blade battery, and the length of the blade battery is 600-1500 mm, the width is 50-250 mm, and the height is 10-100 mm.

[0027] Beneficial effect: The battery includes the above-mentioned battery sealing structure, and thus has the advantages of good sealing effect and low risk of electrolyte leakage, thereby being able to increase the service life of the battery and ensure the safety of battery use. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the specific implementation methods or the description of the prior art. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0029] FIG1 is a schematic structural diagram of a battery sealing structure provided in an embodiment of the present application;

[0030] FIG2 is a schematic structural diagram of a sealing member and a liquid injection hole in a battery sealing structure provided in an embodiment of the present application before welding;

[0031] FIG3 is a schematic structural diagram of a sealing member and a liquid injection hole after welding in a battery sealing structure provided by an embodiment of the present application;

[0032] FIG4 is a partial enlarged schematic diagram of a welding portion in a battery sealing structure provided in an embodiment of the present application;

[0033] FIG5 is a side-sectional metallographic image of a welding portion in a battery sealing structure provided in an embodiment of the present application;

[0034] FIG6 is a schematic structural diagram of another sealing member structure and a liquid injection hole before welding in a battery sealing structure provided by an embodiment of the present application;

[0035] FIG7 is another structural schematic diagram of a battery sealing structure provided in an embodiment of the present application;

[0036] FIG8 is a schematic diagram of the enlarged structure of the liquid injection hole in FIG7 .

[0037] Reference numerals: 10 - cell cover or housing; 11 - liquid injection hole; 111 - first mounting portion; 112 - second mounting portion; 20 - sealing member; 30 - welding portion; 31 - welding point; 40 - elastic member. DETAILED DESCRIPTION

[0038] To make the purpose, 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 clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative efforts shall fall within the scope of protection of this application.

[0039] According to a first aspect of the present application, a battery sealing structure is provided, which includes a battery cell cover or shell 10 , a liquid injection hole 11 and a sealing member 20 .

[0040] Hereinafter, the specific structures of the above-mentioned components of the battery sealing structure according to the present embodiment will be described.

[0041] In this embodiment, as shown in Figure 1, the battery cover and the shell are assembled to form a closed structure, a accommodating cavity is formed inside the shell, and an injection hole 11 is formed on the battery cover or the shell 10 and runs through its main body, and electrolyte can be injected into the accommodating cavity through the injection hole 11; the cross-section of the injection hole 11 can be formed into a circular or rectangular structure, as long as it is ensured that the electrolyte can be injected into the accommodating cavity from the outside of the shell through the injection hole 11.

[0042] In one embodiment, as shown in FIG1 , the battery is a square battery, and the cell cover is correspondingly formed into a long rectangular plate structure or the shell is formed into a rectangular body structure. In another embodiment, as shown in FIG7 and FIG8 , the battery is a blade battery, and the cell cover is correspondingly formed into a rectangular plate structure or the shell is formed into a rectangular strip structure. Both ends of the blade battery in the longitudinal direction may be provided with cell cover plates, wherein at least one cell cover plate may be provided with an injection hole 11; in addition, in other embodiments, the battery is a cylindrical battery, and the cell cover is correspondingly formed into a circular plate structure or the shell is formed into a cylindrical structure. It should be noted that the injection hole 11 on the square battery, blade battery or cylindrical battery can be formed into a structure as shown in FIG8 .

[0043] Furthermore, in this embodiment, as shown in Figures 1 to 3 and Figure 6, the sealing member 20 is welded to the liquid injection hole 11, and the sealing member 20 is formed into a sheet structure that is compatible with the liquid injection hole 11, that is, when the cross-section of the liquid injection hole 11 is circular, the sealing member 20 is formed into a circular sheet structure; if the cross-section of the liquid injection hole 11 is rectangular, the sealing member 20 is formed into a rectangular sheet structure.

[0044] Specifically, the seal 20 is formed with a protrusion protruding toward the injection hole 11, and the protrusion is formed into an annular structure. The edge of the seal 20 is formed into a bend extending away from the protruding direction of the protrusion, so that the bend can fit against the wall of the injection hole 11. The protrusion can be formed by a stamping process, so that a groove is formed on the side of the protrusion facing away from the injection hole 11, and the bend forms part of the groove wall. The provision of the groove provides the seal 20 with elastic deformation space in its radial direction, ensuring that the bend can fit tightly against the groove wall of the injection hole 11, which helps to improve the welding strength between the seal 20 and the injection hole 11.

[0045] In a preferred embodiment, as shown in FIG2 , the top of the seal 20 does not extend out of the outside of the liquid injection hole 11, thereby reducing the axial size of the battery in the liquid injection hole 11, thereby helping to improve the energy density of the battery in batteries of the same volume; in other optional embodiments, as shown in FIG6 , the top of the seal 20 extends out of the outside of the liquid injection hole 11, so that the seal 20 has a certain thickness, which can effectively reduce the deformation of the seal 20 caused by welding and ensure the welding strength of the seal 20 and the liquid injection hole 11.

[0046] In a preferred embodiment, the seal 20 is made of the same material as the cell cover or shell 10 provided with the liquid injection hole 11. For example, the seal 20 and the cell cover or shell 10 are both made of aluminum alloy. The same material has the same temperature and chemical reaction during the melting process, ensuring uniform welding and reducing uncertainties generated during the welding process.

[0047] However, in other optional embodiments, the materials of the seal 20 and the cell cover or housing 10 may be different. For example, the cell cover or housing 10 is made of aluminum alloy, while the seal 20 is made of stainless steel, such as 304 stainless steel.

[0048] Furthermore, in this embodiment, as shown in Figure 3, the welding connection between the seal 20 and the injection hole 11 forms a welding portion 30 between at least a portion of the circumferential side wall of the seal 20 and at least a portion of the hole wall of the injection hole 11. During the welding process, due to the heat of the welding arc, part of the seal 20 and part of the battery cell cover or shell 10 (i.e., the base material) are melted to form a liquid metal pool of a certain geometric shape, that is, the welding portion 30 is a molten pool.

[0049] The molten pool has a penetration depth L1 and a penetration width L2. The penetration depth L1 is the depth of the molten metal on the base material during the welding process, and the penetration width L2 is the lateral width of the molten metal during the welding process. Under normal circumstances, the welding strength is proportional to the penetration depth L1 and the penetration width L2. If the penetration depth L1 is too shallow and / or the penetration width L2 is too narrow, it is easy to cause insufficient welding strength between the seal 20 and the injection hole 11. However, if the penetration depth L1 is too deep, it will also lead to a decrease in the connection quality between the seal 20 and the injection hole 11, and even a risk of welding through. For this reason, in this embodiment, the penetration depth L1 of the weld 30 is 500~1000μm, and the penetration width L2 of the weld 30 is ≥500μm. Within the parameter range, it can ensure that the seal 20 is reliably connected to the injection hole 11, effectively prevent electrolyte leakage, and thus meet the sealing requirements of the battery electrolyte.

[0050] Qualified products are randomly inspected. The specific inspection method is to cut the battery sealing structure along the side after welding and perform metallographic analysis on the welding part 30. The inspection results are shown in Figure 5. The area indicated by the vertical arrow in the figure is the penetration depth L1. After measurement, the penetration depth L1 = 549.17μm, which meets the limit requirement of penetration depth L1 = 500~1000μm; the area indicated by the horizontal arrow is the weld width L2. After measurement, the weld width L2 = 1258.85μm, which meets the parameter limit requirement of weld width L2 ≥ 500μm. Therefore, it is further proved that within the parameter range, the seal 20 can be reliably connected to the injection hole 11, effectively preventing electrolyte leakage, thereby meeting the sealing requirements of the battery electrolyte.

[0051] In a preferred embodiment, the welding portion 30 is formed as a closed annular structure and is clamped between the seal 20 and the injection hole 11, thereby achieving a full circle welding around the seal 20, thereby effectively improving the reliability of the tight connection between the seal 20 and the injection hole 11.

[0052] The compressive strength is the maximum pressure value that an object can withstand. In this embodiment, the compressive strength of the welding portion 30 is greater than 1.2 Mpa, which ensures the connection strength between the seal 20 and the liquid injection hole 11. Even if the battery cell fails and gas is generated in the shell but is not enough to break through the pressure relief member, the seal 20 can still be tightly connected to the liquid injection hole 11.

[0053] The leakage rate can reflect the sealing performance of the welding portion 30 to the liquid injection hole 11 and the sealing member 20. In this embodiment, the leakage rate of the welding portion 30 is less than 1×10 -6 pa·m 3 / s, which can ensure the connection reliability between the liquid injection hole 11 and the sealing member 20 and improve the safety and stability of the battery.

[0054] In this embodiment, as shown in Figure 4, the welding portion 30 can be formed by laser welding. The laser can be a QCW laser. The laser moves along the welding path in the shape of the connection between the seal 20 and the injection hole 11 and emits a pulsed laser to achieve welding. The welding portion 30 is formed by connecting a plurality of welding points 31 in sequence. The two adjacent welding points 31 are partially overlapped. Among the two adjacent welding points 31, along the welding path, the welding point 31 located downstream covers the upper part of the welding point 31 located upstream, and the distance between the two adjacent welding points 31 is the point distance L3.

[0055] In this embodiment, as shown in FIG4 , the overlap rate of two adjacent welding points 31 is not less than 50%, and the overlap rate = (melt width L2 - point distance L3) / weld width L2, thereby ensuring the connection strength of the welding portion 30 connecting the seal 20 to the injection hole 11.

[0056] Furthermore, in this embodiment, the welding power of the laser for forming the weld 30 is 6000-8000 W. When the power is lower than 6000 W, the penetration depth L1 decreases, and when the power exceeds 8000 W, the penetration depth L1 increases.

[0057] In addition, in this embodiment, the energy of the laser used to form the weld 30 is 10-40 J. The energy affects the melting degree of the metal, thereby affecting the size of the weld depth L1 and the weld width L2.

[0058] Furthermore, the welding speed will affect the penetration depth L1. A fast speed will cause the penetration depth L1 to become shallower, while a slow speed will cause excessive melting and weld penetration. In this embodiment, the welding speed of the laser to form the weld 30 is preferably 7 to 10 mm / s.

[0059] In this embodiment, as shown in Figures 2 and 3, the injection hole 11 is formed as a countersunk hole, so that the side wall of the injection hole 11 is formed into a boss structure. Specifically, the two ends of the injection hole 11 in the axial direction are respectively formed as a first mounting portion 111 and a second mounting portion 112. The radial dimension of the first mounting portion 111 is greater than the radial dimension of the second mounting portion 112. After the battery cell top cover is installed on the shell, the first mounting portion 111 faces the outside of the shell, and the second mounting portion 112 faces the inside of the shell. The seal 20 is arranged on the first mounting portion 111. The dimension of the first mounting portion 111 in the axial direction of the injection hole 11 can be 1 mm, and the thickness dimension of the battery cell top cover can be 2 mm.

[0060] In a preferred embodiment, as shown in Figure 3, the ratio of the weld depth L1 to the groove depth L4 of the first mounting portion 111 is K1 = L1 / L4 > 0.5; and / or the ratio of the weld width L2 to the groove depth L4 of the first mounting portion 111 is K2 = L2 / L4 > 0.5; within the limit of this parameter range, the connection reliability between the seal 20 and the injection hole 11 is further improved, effectively preventing leakage of the electrolyte.

[0061] In addition, in this embodiment, as shown in Figures 1 to 3, the battery sealing structure also includes an elastic member 40 arranged on the second mounting portion 112. The elastic member 40 is formed into a columnar structure and is connected to the second mounting portion 112 by interference fit, thereby forming a primary seal for the accommodating cavity injected with electrolyte before the sealing member 20 and the injection hole 11 are welded together, and forming a secondary seal for the sealing member 20 and the injection hole 11 after welding, thereby further improving the sealing reliability of the battery sealing structure.

[0062] In a preferred embodiment, the elastic member 40 is formed from a corrosion-resistant rubber material, such as fluororubber, to prevent electrolyte corrosion and sealing failure of the elastic member 40. Furthermore, at least the portion of the elastic member 40 facing the interior of the housing is tapered, with the radial dimension of the tapered structure gradually decreasing as the elastic member 40 extends into the second mounting portion 112, thereby facilitating insertion of the elastic member 40 into the second mounting portion 112.

[0063] By performing a pressure burst test and a helium detection test on a battery sealing structure in which the depth of penetration L1 of the weld 30 is within the range of 500 to 1000 μm and the width of the weld L2 is within the range of ≥500 μm, it is verified whether the limited range of the depth of penetration L1 and the width of the weld L2 of the present application can ensure that the sealing member 20 is reliably connected to the injection hole 11, thereby effectively preventing electrolyte leakage and meeting the technical effect of the sealing requirements of the battery electrolyte. In addition, a comparison is made for battery sealing structures in which the depth of penetration or the width of the weld is less than 500 μm. For specific experimental verification, see the table below:

[0064] The experimental results of the parameters shown in the table above show that in Examples 1 to 12, the penetration depth L1 of the weld 30 is within the range of 500 to 1000 μm and the weld width L2 is within the range of ≥500 μm. The blasting test shows that the blasting strength of Examples 1 to 12 is greater than the compressive strength of the weld 30 of 1.2 MPa, which proves that the welding strength of the seal 20 and the injection hole 11 meets the requirements. The helium test test shows that the leakage rate of the weld 30 is less than 1×10 -6 pa·m 3 / s, proving that the sealing of the battery electrolyte meets the requirements.

[0065] In Comparative Examples 1 to 6, although the weld width L2 is in the range of ≥500 μm, the weld depth L1 is less than 500 μm. The blasting strength of Comparative Examples 1 to 6 is less than 1.2 MPa as measured by the blasting test, and therefore the compressive strength requirement of the weld 30 is not met. In Comparative Examples 7 to 12, although the weld depth L1 is in the range of 500-1000 μm, the weld width L2 is less than 500 μm. The blasting strength of Comparative Examples 7 to 12 is less than 1.2 MPa as measured by the blasting test, proving that the compressive strength requirement of the weld 30 is not met. In addition, the leakage rate of the weld 30 of Comparative Examples 7 to 12 is greater than 1×10 -6 pa·m 3 / s, proving that the sealing of the battery electrolyte does not meet the requirements.

[0066] In summary, this further proves that under the limited conditions of ensuring the penetration depth L1 of the weld 30 = 500-1000 μm and the weld width L2 of the weld 30 ≥ 500 μm, the connection strength between the seal 20 and the injection hole 11 can be reliable, thereby meeting the sealing requirements of the battery electrolyte.

[0067] According to a battery sealing structure provided in the present application, the seal is welded to the injection hole to form a welding part at the connection. By limiting the size of the weld depth L1 and the weld width L2 of the welding part, the seal is reliably connected to the injection hole, effectively preventing electrolyte leakage, thereby meeting the sealing requirements of the battery electrolyte.

[0068] According to the second aspect of the present application, a battery is provided, which can be formed as a square battery or a blade battery. When the battery is a square battery, the length dimension of the square battery is 100-600 mm, the width dimension is 50-250 mm, and the height dimension is 10-100 mm; when the battery is a blade battery, the length dimension of the blade battery is 600-1500 mm, the width dimension is 50-250 mm, and the height dimension is 10-100 mm.

[0069] According to a battery provided in the present application, including the above-mentioned battery sealing structure, the sealing member in the battery sealing structure is reliably connected to the injection hole, effectively preventing leakage of the electrolyte, thereby meeting the sealing requirements of the battery electrolyte, thereby improving the battery yield and service life, and ensuring the safety of battery use.

[0070] The above is a detailed introduction to the single cell and battery pack provided in the embodiments of the present application, and specific examples are used to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the technical solutions and core ideas of the present application; ordinary technicians in this field should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application. Industrial Applicability

[0071] The battery sealing structure of the present application welds the seal to the injection hole to form a welded portion at the connection. By limiting the size of the weld depth L1 and the weld width L2 of the weld, the seal is reliably connected to the injection hole, effectively preventing electrolyte leakage, thereby meeting the sealing requirements of the battery electrolyte, thereby improving the battery's yield and service life, and ensuring the safety of battery use.

Claims

1. A battery sealing structure, characterized in that: The battery sealing structure includes: The cell cover or housing is formed with a liquid injection hole penetrating through the body thereof; A sealing member is welded to the injection hole, so that a weld portion is formed between at least a portion of the circumferential side wall of the sealing member and at least a portion of the hole wall of the injection hole, wherein the weld depth L1 of the weld portion is 500 to 1000 μm, and the weld width L2 of the weld portion is ≥500 μm; The injection hole is formed as a countersunk hole, so that the side wall of the injection hole is formed into a boss structure, and the two ends of the injection hole in the axial direction are respectively formed as a first mounting portion and a second mounting portion, the radial dimension of the first mounting portion is larger than the radial dimension of the second mounting portion, and the sealing member is provided on the first mounting portion; The ratio of the penetration depth L1 to the groove depth L4 of the first mounting portion is K1 = L1 / L4 > 0.5; And / or, a ratio of the weld width L2 to the groove depth L4 of the first mounting portion K2 = L2 / L4 > 0.

5.

2. The battery sealing structure according to claim 1, characterized in that: The compressive strength of the welding portion is greater than 1.2 MPa.

3. The battery sealing structure according to claim 1, characterized in that: The leakage rate of the welding part is less than 1×10 -6 pa·m 3 / s.

4. The battery sealing structure according to claim 1, characterized in that: The welding power for forming the welding portion is 6000-8000W.

5. The battery sealing structure according to claim 1, characterized in that: The energy for forming the weld is 10 to 40 J.

6. The battery sealing structure according to claim 1, characterized in that: The welding speed for forming the welded portion is 7 to 10 mm / s.

7. The battery sealing structure according to claim 1, characterized in that: The welding portion is formed by sequentially connecting a plurality of welding spots; the overlapping rate of two adjacent welding spots is not less than 50%, wherein the overlapping rate = (L2-L3) / L2.

8. The battery sealing structure according to claim 1, characterized in that: The sealing member is made of the same material as the cell cover or shell provided with the liquid injection hole.

9. The battery sealing structure according to claim 1, wherein: The battery sealing structure further includes: The elastic member is arranged on the second mounting portion.

10. A battery, characterized in that: A battery sealing structure comprising the battery sealing structure according to any one of claims 1 to 8; The battery is a square battery, and the length of the square battery is 100-600 mm, the width is 50-250 mm, and the height is 10-100 mm; Alternatively, the battery is a blade battery, and the length of the blade battery is 600-1500 mm, the width is 50-250 mm, and the height is 10-100 mm.

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